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5 - Aeration : 


  One of the oldest method in the fresh water aquarium for gases exchange in the aquarium and it is used in the early stages of aquarium development when the filters yet not invented ..Water movement and circulation serves to oxygenate the water so that fish have the air they need to breathe and survive. However, in an aquarium, the surface of the water is greatly reduced. Therefore, artificial ways of oxygenating the water must be accomplished through aeration. There are several ways to aerate your aquarium and these methods will be discussed in this article.

Before discussing specific methods, it is important to address the surface area of the water in your aquarium. The greater this surface area is, the more water that is in contact with the air at any given moment. This leads to greater oxygen absorption by the water. Therefore, you should try to maximize the surface area in your aquarium. This issue is particularly important to consider when you are thinking about the shape of a tank – standard tanks are rectangular with a greater width than height but some tanks come in “tall” sizes with walls that are taller than they are wide. Many people mistakenly assume that you can keep the same number of fish in a 20-gallon standard tank as you can in a 20-gallon tall tank. However, the 20-gallon standard tank actually has a larger surface area due to its length and width dimensions. You need to be careful with tall tanks or irregularly-shaped tanks (such as hexagons), as the water surface can be fairly small. This smaller surface limits the stocking capacity of the aquarium.


Oxygen/Carbon Dioxide Exchange Basics:


As your fish breathe, they absorb oxygen from the tank water and their bodies convert it into carbon dioxide which is then exhaled. Oxygen and carbon dioxide are also exchanged at the water’s surface -- carbon dioxide is released from the water into the air. This is important because your fish would die if the CO2 was never allowed to escape into the atmosphere – it would simply build up in the tank, causing your fish to slowly suffocate.


Air pump , pipes and diffusers :  

Usually bignner hobbies or casual hobbies or any fan with limited budget normally go for air oump .. Air pump is the  devise used to generate bubbles in the water ..flexiable pipes used to transport the air to the aquarium and air stone or air diffusers responsible to generate the proper bubbles . 

    All Air pumps works out of the Water for safety Air pump level should be up the aquarium to avoid and water back to the air pump 

Air Pump connected to the pipe and then to Air stone 




1- Bigger bubbles will disturb the aquarium and the fishes inside and not good for the aeration process . 

2- Mid size bubbles which proper to the aquarium .

3- Small Bubbles also good 

Large Air Pump for commercial used or for multi tanks 

  Air Pump can feed two air stone 

Air Stone .. is manufactured from compressed sand . 

 Up and below the fexiable air diffuser can shape in any form that hobbyist  want 

6 -  Water Chiller : 



     Sometimes refer to this equipment as an optional but it will be mandatory when the aquarium installed in the hot climate or Air-conditioning system not work in the room that contains the aquarium .. Before install this devise be sure if you need it or no by knows if the Air condition unit work permanently or not and weather it will be set on 25C , Usually aquarium Acquire the same air temp. Surrounding. 


A constant, appropriate water temperature is vital to keeping your aquarium inhabitants healthy. A sudden temperature change can place undue stress on your aquatic life, increasing their susceptibility to infection and disease.

Aquarium setups, reef aquariums in particular, often employ equipment (lighting and water pumps especially) that produce enough heat to raise water temperature. Without a chiller to decrease water temperature, aquarium water can warm to a point where it no longer holds enough oxygen to sustain the inhabitants.

If you need a chiller, plan to install it into your system as early as possible. Chillers are external units that often require plumbing and always require adequate space and sufficient ventilation. They give off significant amounts of heat when in use - in fact, you should avoid placing your chiller in an enclosed aquarium stand, because it can give off enough heat to raise water temperature. It may also cause the chiller to overheat and not work as effectively.

The word "chiller" may be a misnomer. A chiller does not create cold, but actually removes heat. The ability of a chiller to remove heat is measured in BTUs (British Thermal Units). One BTU will raise one pound of water (approximately one pint) 1°F. A unit with a higher BTU is more efficient and will remove heat faster than one with a lower BTU. A chiller operates similar to a refrigerator or air conditioner. The refrigerant gas picks up heat from the aquarium water and then delivers it to the radiator as the gas pressure is dropped. A fan then dispels heat from the radiator.

Types of chillers: 

- Thermoelectric Chillers

Quiet, energy-efficient thermoelectric chillers are intended for use with smaller freshwater and saltwater aquariums (less than 55 gallons) and insulated bait/specimen tanks with a slow water flow. Thermoelectric chillers are not effective on large aquariums with a fast water flow.

- In-Line Chillers

Intended for use on larger systems with in-line filtration, in-line chillers cool already-filtered water, and are used primarily with saltwater reef setups. In-line chillers are available in several sizes (from 1/5 to 1 HP), and therefore work with several sizes of aquariums. These chillers require plumbing, and should be incorporated into the overall aquarium plan prior to execution.

- Drop-In Chillers

Drop-in chillers have a probe that is placed directly into wet/dry filters or any filter with a sump, and are used primarily with saltwater reef setups. Drop-in chillers are available in a variety of sizes (1/5 to 1/3 HP) and are ideal for systems with minimal space and the need for easy setup (since they require no plumbing).

Factors to consider when choosing a chiller

When choosing a chiller, consider the size of your aquarium and sump, your aquarium setup, and additional equipment and the heat it generates. An estimate of the maximum temperature your setup may produce and the temperature requirements of your aquarium inhabitants are also very important considerations when choosing a chiller. In order to choose a chiller, you will need to calculate the amount of "pull-down" you will need. To do this, subtract the temperature at which you want your aquarium to be from the maximum temperature you think will be produced in the aquarium during the peak heat during the summer. Here is an example on how to determine pull-down:

Estimated maximum 
desired aquarium  temperature    
    -      Desired  aquarium  temperature   =    Pull-down


 Example: 90°F – 75°F = 15°F pull-down


Choose a chiller that effectively cools your aquarium water in the space and setup you have allotted. If your cooling requirements are on the upper end of what is recommended, choose the next largest chiller to ensure an adequately cooled aquarium and healthy inhabitants. Using the table below, if you have a tank size of 225 gallons and you need an estimated pull-down of 15°F, the 1/5 and 1/4 horsepower units would be too small; you would need a 1/3 hp unit. Some expert aquarists recommend to always get an over-sized chiller since it may save on electricity by not needing to run as long.

HP       SuggestedTank      Min/Max                                    Maximum Tank Size for Degrees 

           Size(in gallons)        FlowGPH                                    of Pull-Down Needed

                                                                                               10°F         15°F           20°F             25°F

1/5          55-225                    360-900                                 225         120             80               55

1/4         80-320                    480-1200                                320         175             110              80

1/3        125-475                   600-2100                                320          175            110               80 




 In the better models of chillers, the heat exchanger and compressor are held rigidly together, NOT with a flexible connection. The two metals most commonly used in the heat exchanger are titanium, and Teflon-coated copper. Titanium is expensive and is not a good conductor of heat, however, it is impervious to the saltwater that can corrode many other types of metal. When using coated copper, routinely perform a visual inspection of the unit. Any crack in the coating can expose the copper to the saltwater and result in increased copper levels in the water, with possible toxicity and death of the inhabitants.

 The Chiller Connection to the tank :

1-  suction pipe to chiller .

2-Return water to the Tank .

3-Pump for water intake 

x - Distance from wall should be minmum of 20 cm 

7- Other Equipments and Supplies : 


   - UV : 


What does a UV sterilizer do?

A UV sterilizer is used to control infections by stopping the spread of microorganisms from one fish/coral/invertebrate to another through the water. It is also used in pond applications to control free-floating algae. When operated correctly, free-floating microorganisms will be killed by the UV light. Note that the organisms must be in the water that flows to the UV sterilizer. The UV light has no residual effect and will not kill organisms attached to fish (e.g., adult stage of ich) or rocks (e.g., algae).

How do UV sterilizers work?

The UV sterilizer utilizes a germicidal fluorescent lamp that produces light at a wavelength of approximately 254 nanometers (2537 Angstroms). The water with the bacteria/algae passes over the bulb (or around the bulb if a quartz sleeve is used) and is irradiated with this wavelength. As the light penetrates the bacteria/algae, it mutates the DNA (genetic material), preventing growth/multiplication of the organism.

What factors influence the effectiveness of UV sterilizers?


  • Size and type of organism: Theoretically UV radiation can kill viruses, bacteria, algae, and protozoa. In general, larger organisms, such as protozoa, require a higher dose of UV radiation than smaller organisms, such as bacteria. But there are also differences between various organisms of the same type: some bacteria are more resistant to UV radiation than others.

  • Power of bulb: The amount of UV light produced by the bulb is reflected in the wattage of the bulb. Bulbs with a higher wattage produce more UV light. The ability of the germicidal fluorescent lamp to produce UV light decreases with age, and in most cases, the bulb needs replacement every 6 months. UV light is best produced at temperatures of 104-110ºF; cooler temperatures will result in less output.

             Organism*                                                              Killing Dose of UV light
                                                                              (Microwatt seconds per square centimeter)  

                Viruses                                                                             15,000

                Bacteria                                                                      15,000 - 30,000

               Algae                                                                            22,000 - 30,000

               Fungi                                                                                   45,000

              Protozoa                                                                              90,000

*Note: These are generalities; some specific organisms in these groups may require more or less of a dose than indicated.


  • UV penetration: If the UV light can not penetrate the water, it will not be effective. Higher water turbidity will decrease penetration. UV sterilizers should be placed after the biological and mechanical filters so the water is as clear as possible when it enters the sterilizer. Salinity also affects penetration; UV light penetrates freshwater better than saltwater. Finally, cleanliness of the lamp or sleeve is important. If a film or mineral deposit covers the lamp or sleeve, the light will be partially or totally blocked. The distance of the lamp from the water also influences the effectiveness. UV light will only penetrate clear saltwater to a depth of 5mm.

  • Contact time: The longer the amount of time the water is being exposed to the UV light, the more killing power is available. The contact time, sometimes referred to as "dwell time," is influenced by flow rate of the water: slower flow rates increase contact time. The length of the bulb also affects the contact time; with a longer bulb, the water is in contact with the UV light for a longer period of time. Another variable to consider is the turnover time (amount of time required to have the entire volume of water in the aquarium pass through the sterilizer). Since the "sterilized" water constantly mixes with the water in the aquarium as it returns, it is impossible to "sterilize" all the water in the aquarium. That would only be possible if all the water would be removed, sterilized, and then returned to the aquarium at one time. This may result in sterilized water, but would certainly raise havoc with the aquarium inhabitants! Calculating turnover time is mathematically difficult, but can be approximated with the following formula

 9.2  x  gallons in tank   / flow rate in gallons per hour    = number of hours for one turnover


Temperature: UV light is best produced at temperatures of 104-110ºF; cooler temperatures will result in less output. Quartz sleeves help to insulate the bulb from the cooler aquarium water and thus maintain a higher UV output.


In which types of systems should UV sterilizers be used and what are the benefits?

A UV sterilizer may be used in any aquarium, however, in smaller aquariums (less than 24 gallons), the cost of the unit may make it impractical. UV sterilizers are most helpful in multiple tank systems that share a common filter. In a single tank system, they are beneficial in controlling the spread of an infectious disease if one occurs. This is especially true in heavily stocked tanks and those with large amounts of live rock and corals that could make catching and isolating a diseased fish difficult, or the use of certain medications contraindicated. Disease control is especially important when adding new fish to an established aquarium, since 98% of the hobbyists do not use a quarantine aquarium.

In ponds, UV sterilizers are one of the best ways to control free-floating algae, allowing the pond owner to see and enjoy the fish. The UV sterilizer will also kill free-floating bacteria in the pond water.

What are the limitations and potentially harmful side effects of UV sterilizers?

UV sterilizers are NOT a replacement for good biological and mechanical filtration, regular water changes, and proper control of the nitrogen cycle. A UV sterilizer should be considered as an insurance policy.




UV sterilizers will be ineffective against string algae or other nuisance or disease-causing organisms that are not free swimming in the water.

While the UV sterilizer will usually do no harm, it should not be used when first cycling the aquarium, as it may kill beneficial bacteria before they attach to the bio-media or gravel.

Many medications can be "denatured" by the UV light, so the sterilizer should be turned off when using medications, especially chelated copper treatments. The UV light will "break" the bond of the chelating agent, and the aquarium will have a sudden, lethal concentration of ionic copper.

The UV sterilizer can be used to control parasites, but the flow rate required is so slow that it is somewhat impractical on larger aquariums, unless larger (40W+) UV systems are used.

UV sterilizers can heat the water as it passes through, especially if the unit is larger than necessary for the tank size. A chiller may be necessary to keep the aquarium water at the appropriate temperature.


What styles of UV sterilizers are available?

The styles of UV sterilizers relate to their orientation when in use (horizontal or vertical) or their position in the water flow (in-line or hang-on). All vertical units must be used vertically, while some of the horizontal (Rainbow) units can be used vertically as well as horizontally. Some styles can be used in-line or hung on the back of the tank. Specialized units are designed to be used in outdoor/pond applications.

A newer style of UV sterilizer, called the "double helix," increases the contact time between the water and the UV light because the water makes a double spiral pass over the tube.

Models may or may not have a quartz sleeve. Those with a sleeve are sometimes called "dry bulbs." Cold water systems must have a quartz sleeve to maintain the proper output of UV light. A sleeve makes periodic cleaning and bulb replacement easier.

According to Robert Fenner, a well-known aquarist, author, and speaker, features of a good UV sterilizer include:

  • A separate (remote) ballast unit that can be positioned in a place free of heat and water damage

  • An indicator light to check for "on" operation

  • An "automatic on" feature to turn the UV unit back on in the event of a temporary power loss

  • Couplings that are easily fitted to your system

  • A quartz or teflon sleeve at little or no additional cost

  • All noncorrosive water-contact surfaces

  • Acceptable guarantees and warranties

How is the correct size of a UV sterilizer determined?

This is about the only "complicated" part to the use of a sterilizer. For proper use, the UV sterilizer must be matched to the proper flow rate to ensure an efficient "kill dose" for the organisms you wish to eliminate. This flow rate must be matched to the size of the aquarium to ensure the proper number of "turn-overs" of the water. Most manufacturers will provide a table that recommends the maximum aquarium size and appropriate flow rate for each model they make. When comparing manufacturers, realize ratings may differ as to whether they take into account:

  • Bulb efficiency: Some use 100% efficiency, others a lower efficiency (e.g., 60% observed towards the end of the bulb life)

  • Organism to be killed: Bacteria/algae or protozoa

  • Water clarity: Clear or turbid

  • Transmission loss through the quartz sleeve

These differences make it very difficult to provide general rules of thumb. Check with the manufacturer if you are unsure on how the ratings are calculated.

The table at the right compares several manufacturer's recommendations, which vary considerably. The wattage recommended by Emperor Aquatics are dramatically higher because they apply a 0.45 absorption coefficient factor for water clarity, factor in a 20% transmittance reduction for the quartz sleeve into the formula, and represent the lamp's operating performance when new and at the end of useful life (60%). This compensates for loss of UV radiation traveling through turbid green water and the sleeve's glass, while also taking into account lower efficiencies of older bulbs.

 UV sterilizers are NOT a replacement for good biological and mechanical filtration, regular water changes, and proper control of the nitrogen cycle.

 Manufacturer/Model       Watts       Maximum Gallons       Maximum Flow Rate


Aqua Ultraviolet                    15                      500                              700

Angstrom 2537                      30                     500                              750

Double Helix                          36                     500                              500

Emperor Aquatics                 65                     400                              952

Emperor Aquatics                 80                     400                            1049


How is a UV sterilizer installed?

The UV sterilizer should be the last piece of equipment in the system before the water is returned to the aquarium. It should be preceded by the biological and mechanical filters, and any chemical filter or heat exchanger in the system. Follow the manufacturer's directions on installation. Most units use hose barb connectors to attach to the appropriate water pump or are designed to allow add-on connectors as a PVC slip fit or hose barb attachment.

What is the proper maintenance schedule for UV sterilizers?

The quartz sleeve will need to be checked monthly and removed and cleaned with rubbing alcohol. Some larger UV sterilizers have wiper mechanism units installed for easier maintenance.

For most units, the UV bulb will need to be replaced after 6 months of continuous use, however, this time may vary so be sure to follow the manufacturer's recommendations. When installing or changing a bulb, never look directly at the bulb when the unit is turned on. Doing so can result in permanent damage to your eyes. (The damage can occur without you feeling any discomfort.)

Always disconnect the unit from the electricity when performing maintenance to protect against possible shock. When turned on, the bulb becomes especially hot when in the air and submerging it in water may cause it to break.

References and Further Reading

Fenner, RM. The Conscientious Marine Aquarist. TFH Publications, Neptune City, NY. 2001.

Tullock, JH. Successful Saltwater Aquariums. Energy Savers Unlimited, Carson, CA.1994.

Quality Marine.

  1- UV Lamp .   2-Electrical cable. 3-Water in  4- Water Out 

   Below the UV Connection With External Filter

- Aquarium Background: 

    It is normally that the rear glass sheet of the aquarium will be covered by a proper poster, some of them are inside the aquarium, other are outside aquarium, and also you can make a three dimensional background using foam board and foam spray , and colored by cement color to reflect the natural colors of rivers and lakes bottoms .. Also you can paint the back  glass with Blue color from outside ..


  Posters to be used  out of the aquarium

   You can build a beautiful and realistic Unleash your imagination for different types of backgrounds which replicates the real under water environment 


- Toys : 

    You can use several types , shapes with different colors of moving toys which move by air pressure from Air pump instead of air stone .

     But is this natural it is safe? the answer is No .. Some of them have a sharp edges and others can disturb the aquarium .. Nowadays it is less spread among the hobbyists.. 


-Electronic devices :

        The revolution of electronics enter everything in our life , Aquarium also have a volume of it  , usually use to monitor the aquarium or test the water ,  Understanding what is happening inside your aquarium is vital to ensuring that the aquatic life remains healthy. This revolutionary water monitoring device allows you to continuously track the changes in the water parameters, alerting you to the problems before they affect the fish.  It is optional and used for advance hobbyists and for some hard and unique projects and aquariums.. 


    Several types of electronic equipments used to moniter the aquarium and for multy functions.. 

    In the Fresh water Aquarium: Tank, Heater, Filter and lighting are essential  

     Salt Water Aquarium Components : 



1-   Tank .

2-   Heater.

3-  Lighting.

4-  Filter .

5-    Protein skimmer   .

6-  Sump tank

7-   Pumps and Power Heads .

8-  Accessories and Others . 


1- Tank : 


       The Same tank can be used to establish a marine Aquarium , Please refer to the Aquarium Tank in fresh water aquarium components by clicking here ..


​      Moreover the Acrylic tank is popular more than the glass tank especially with hobbyist how want to build their aquarium by themselves as a DIY ( Do-it-Yourself ) project because it is included several holes needed to be cut for plumbing works ..


     Aquariums built to be a salt water ot marine aquariums and made from Acrylic sheets  - Notice the out brazing to put more rigidity for the tank ..

      All Public Aquarium construction from Acrylic Sheet and the thickness may be up to 40 cm ?!!

      Acoral display aquarium made from Acrylic 

      Acrylic sheet joint my sepecial acrylic which weld both sheets together 

      Clear acrylic sheets 

       To make bend in acrylic sheet two wood borads wth hinges and thermo wire enough for it ?!

     2- Heaters :

               Same heaters that we use it in the fresh water aquarium we can use it also in the Salt water aquarium .

     For more information about heaters by clicking here . be sure from the room temperature and A/C if it is table 24- 25 c may be you will not need to use the Heaters . 


     3- Lighting :

                You can have all the water chemistry right but without proper lighting you and your tank inhabitants are doomed. Corals and many invertebrates have symbiotic algae that create food and energy for them. Like plants, they require light for photosynthesis to create the food and energy they and their host need to survive. Understanding lighting starts with understanding the lighting needs of your tank inhabitants and then how best to meet them with the lighting options available. One thing you will realize rather quickly is that there are multiple options and no definitive “if you have this you need that” answers. It is also important to know that keeping lights on longer will not compensate for incorrect spectrum or intensity.

                 So what is going in this tank?

Knowing what you plan to put in the tank is key to deciding the lighting system you will need. A fish only tank generally only needs light to view the inhabitants. Add live plants or corals and you need to supply them with appropriate light spectrum sources and intensity to allow photosynthesis – in essence you are replacing their natural light source – the sun. And different corals have different lighting needs some liking more intense light, others medium or low. Creating a species light requirement chart for your anticipated tank inhabitants will aid in the decision making process. The chart below is a general guideline but even within these groups there are variations:





                                  Anemones           Corallimorphs         LPS Corals         SPS Corals       Soft Corals       Zooanthids


Needed                      Low to Moderate     Low to Moderate   Low to Moderate        High       Moderate to High   Low to Moderate 



Tank Placement           Sand Bed                     Lower             Middle                        Upper                    Lower                     Lower

(general depth)




All light is not the same – Spectrums


Light is made up of a variety of wavelengths (measured in nanometers, nm)
that translate into different hues (colors) and hence the term spectrum. The
sun produces 3 wavelengths of light:

  • UVA: The visible wavelength of light and essential to photosynthesis. Actinic light is a particular portion of this spectrum (420nm) important to marine organisms. Red, orange and yellow light colors are referred to as warm; green and blues are referred to as cooler colors.

  • UVB: This is the non-visible wavelength of lighting. It is what gives us a suntan.

  • UVC: This wavelength is used for ultraviolet sterilizers which kill harmfulbacteria. This wavelength is very dangerous to all animals.

The different lengths of light waves do not penetrate through the water equally. Red light is the first to be filtered out and can only penetrate a short distance. Next lost are orange and yellow as light waves penetrate deeper. Greens and then blues will penetrate the water deeper, providing essential energy sources to the algae hosted in coral. Of all the colors of the spectrum blue light penetrates the deepest. And there is a slight difference in penetration between salt and fresh water with saltwater absorbing slightly more energy due to its higher density.


Measuring light and what those numbers mean


When you purchase aquarium lighting you will see different terms that describe the type, intensity, and color of the light they produce. Knowing what these mean is essential to understanding what they will do to and for your tank inhabitants.




The Kelvin Light Temperature of lights is not temperature in the sense of being hot and cold like boiling and freezing water. It comes from the lighting industry as a means to measuring the color temperature of a bulb. Aquarium lighting bulbs are rated by color temperature measured in degrees Kelvin (K) to indicate the hue of a specific light source. Color temperatures over 5500K are termed cool colors (green-blue) and the higher the K value the bluer the light appears. Bulbs under 3000 K are referred to as warm colors (yellow-red) and the lower the K value the more yellow then red light appears. 6000K is where the ratio between red and blue is equal. The human eye mostly sees light around 5500K. A typical summer day is 6500K. Higher value K lights penetrate water more deeply, even more so in saltwater, and the higher the K, the more blue the light becomes.




The nanometer is a unit of length in the metric system, equal to one billionth of a meter. It is used to measure very small lengths of many things, including the wavelengths of light. Remember ROYGBIV – red, orange, yellow, green, blue, indigo, violet? The visible light spectrum ranges from a lower wavelength 400 nm (violet) to the higher wavelength 800 nm (red). Below 400 you find Ultraviolet (UV) wavelength and above 800 is Infrared (IR). Wavelength differences determine how the wave affects its surroundings and is why short-wave UV light can destroy DNA and visible light does not. UVC bulb will spike at about 265 nm, an actinic at about 420 nm, and a daylight bulb about 700N. Different spectra are required for different species depending on their natural latitude and water depths. Most corals contain symbiotic algae (zooxanthellae) that require light in the actinic UVA range (400-550nm ) to facilitate photosynthesis.














LUX – lx:


This is a measure of light intensity over a given area and very important to most corals in reef aquariums. Too low a light intensity and the zooxanthellae do not create sufficient oxygen. Lux in tropical reefs measures between 110,000 and 120,000 lux at the surface of the reef and 20,000-25,000 Lux one meter below the surface. For reef aquariums, look for a minimum intensity of no less than 3,000 lux for light reaching the deepest part and no more than 100,000 to 120,000 as too much light can have adverse effects also. One lux is equal to one lumen per square meter and is measured with a luxmeter. Lux are also expressed in watts/meter2 but there is a different conversion factor for every wavelength, and it is not possible to make a conversion unless one knows the spectral composition of the light.






Stands for PhotosyntheticallyActive Radiation and is spectrum range of sunlight, from 400 to 700 nanometers, needed by plants and zooxanthellae algae for photosynthesis. This range is found from actinic UVA (400-550nm) to near infrared. UVA is the absorption bandwidth of chlorophylls a, c², and the light-harvesting carotenoid peridinin, a pigment related to chlorophyll. There are three main spikes in the PAR spectrum (one 400-550nm, two in the 620-720nm range) All three are generally found in a daylight bulb of approximately 6500K. Most symbiotic zooxanthellae and other green algae need more of the actinic spike in the 465-485nm range. (Most actinic bulbs however are in the lower 420nm except for the newer LED lights which have a more precise 465-485nm blue.) For this reason extra actinic bulbs are often included in reef tanks (for corals and clams with zooxanthellae and limited in freshwater tanks to control blue-green algae growth.


Is Photosynthetically Usable Radiation or commonly referred to Useful Light Energy and is the fraction of PAR that is absorbed by zooxanthellae photo pigments that stimulate photosynthesis. So while certain type bulbs produce PAR, the percentage of useful light bands for your tank inhabitants may not be optimum. And even
though two different lights may look to produce the same light to our eyes, they may be producing a significant amount of light in a range not needed (such as the yellow-green spectrum) or used by your particular tank inhabitants. This is why what you see isn’t what you need, and why even enough of the wrong light can still produce enough of the right light.


Are the measure of how bright or intense the light looks to our eyes; the higher the lumen the brighter the light looks to us. Lumen per watt is useful to know when comparing bulb outputs and is figured by taking the lumens listed by the manufacturer and dividing by its rated watts. This comparison does become deceiving when looking at newer LED lights which have more focused light energy with little light energy lost so a LED light often requires half (of less) the lumens to provide the required essential light energy. Because of this, lumens are only part of the equation when figuring out your lighting needs.


Watts are a measure of energy being used, not energy being output. It is equal to one joule of energy per second. Back when lighting choices were limited to bulbs like T12’s, watts per gallon was a reasonably accurate way to work out lighting needs. Advances in lighting have produced bulbs that spread out more watts in shorter distances. Using the traditional 2-3 watts per gallon for plants and 3-5 for reef as the sole determination of tank lighting needs is really not an accurate measure and is just a starting point, not a rule.


Is Color Rendering Index and indicates how a color will appear under different light sources and is the only agreed upon international system to describe what we really see. If a light source doesn’t change the appearance of light compared to a reference source of the same color temperature, it has a CRI of 100. CRI came about as a way to compare continuous spectrum sources whose CRI’s are above 90; below 90 two sources with the same CRI can render color very differently In selecting proper aquarium lighting it is not an important parameter.

So how do I combine all these to help me make my decision? Over time, the experiences of aquarists and actual testing has produced these observations relating these measures to providing optimal tank inhabitant growth and health:

  • Because coral receives intense, direct tropical sunlight, the focus was once on simulating this with 6500K lights. 6500K lights produce the best growth results for fresh water plant tanks and can be used in reef tanks more successfully when used in combination with other light spectrum sources. Blue actinic 50000K or adjustable/multiple LED can be added to balance and increase depth penetration and first blue spike in PAR if using 6500K lamps in marine tanks.

  • 10000 K bulbs can bee a good choice for better PAR, depth penetration and growth with soft corals, LPS, and SPS (but noted slower growth).

  • 14000 K bulbs penetrate more than 10000K while still providing a useful PAR.

  • 20000 K bulb will bring out the fluorescent pigments in many corals. They are used for this reason and in deeper tanks but are not good as the only Kevin temperature lights in a reef tank.

  • 50000 K is the general Kelvin rating of actinic blue light sources. It is a good compliment to 6500, 10,000, 14,000 Kelvin lights in tanks with inhabitants with zooxanthellae algae.

  • Actinic blue lighting beneficial to photosynthetic invertebrates, is also pleasing to the eye when used to supplement your daylight light choice.

  • Fluorescent and incandescent lights produce a lot of yellow and green light which research shows is mostly wasted energy for SPS coral and freshwater plant needs.

  • Lux or light intensity, is crucial to most reef tanks and a minimum of 3,000 lux at the tanks deepest point is suggested with a 100,000 to 120,000 maximum at the surface.

  • Reef tank inhabitants that depend on the photosynthesis of zooxanthellae algae will best thrive with light that achieves the optimum PAR, which includes daylight from 6500-14000K.

  • Light brightness is not an indicator of the light energy spectrum the bulb produces. For example, LED light may seem less bright but the actual spectral energy output is much higher and can be more accurate to your tank inhabitants needs.

  • So while watts per gallon are a place to start, it doesn’t take other important factors into account to ensure you completely meet the needs of your tank’s inhabitants.

  • It is a common practice among reef hobbyists to combine different types of lighting bulbs to create the proper intensity and spectrum for the inhabitants of a given reef tank. There are many possible combinations so talking with others, researching forums, and experimentation will help you find the right combination for your tank





 Deciphering the different types of bulbs and lights:

For a fish only aquarium you can use any type of lighting you wish to. If you are going to be keeping live plants or live corals in the tank you will need a lighting system that will provide plenty of light for the plants and symbiotic algae found in corals to photosynthesize. This can be accomplished using multiple NO output bulbs over the tank or high output lights such as a VHO, PC or T5 fluorescent fixture or a MH system. What does that all mean? Keep reading just a bit further!

Don’t forget to consider expected bulb life and the cost of replacements. Bulbs dim over time and this is not necessarily noticeable to human so it is best to replace bulbs on a schedule to ensure proper lighting needs are met. Also consider how you are mounting the fixtures themselves. Fixtures come as fully assembled, that is ready to go right out of the box, and as retrofit kits. You will find them with mounting legs that let you set the fixture right on the rim of the tank or as hanging kits that let you suspend the light over the tank. Retrofit kits usually work best with a custom canopy, mounting inside with a few screws.


Normal Output Fluorescent (NO): These are the standard wattage bulbs included with many stock aquarium hoods. They use a fluorescent starter to regulate the flow of electrical current through the lamp tube. The linear bulbs are double ended and come in many lengths and watts. Because they produce little in intensity compared to other lighting types they are inappropriate for reef system tanks and are seen more often in fresh water or FOWLR tanks. A starting point would be bout 2-5 watts per gallon of water.

High Output Fluorescent (HO): 

These have a higher lumen output than VHO, generate less heat, and are more energy efficient. They require an electronic ballast and come in different diameters, wattage, and lengths. They can last considerably longer, between 2-3 years, with less degradation in lumen output. Option for reef tanks or tanks with live plants. A starting point would be about 1-3 watts per gallon of water.



 Very High Output Fluorescent VHO


Very High Output Fluorescent (VHO): 

Allow you to fit fewer bulbs over your tank and provide substantially more lumens compared to NO bulbs power usage and intensity is about 3 times that of NO bulbs but they generate less heat than metal halides. VHO bulbs are 1.5″ (T12) diameter linear fluorescents available in different wattages and lengths. They require a 1500ma VHO ballast to operate and you can expect to replace them about every six months. Their higher light intensity and more even spread allows for a greater variety of corals to be kept, including most soft corals, most LPS corals, and some SPS corals. Option for reef tanks or tanks with live plants. A starting

point would be about 1-3 watts per gallon of water.



Power Compact Fluorescent (PC or CFL)

Sometimes called compact fluorescent, they are brighter and more energy efficient than NO fluorescent bulbs. They use a technology similar to VHO but have a ‘U’ shape form and are powered from just one end. Bulbs are single ended and come in 2-pin, 4-pin, and 4-pin straight configurations in multiple watts, shapes, and lengths. They allow for more wattage in a single space. Option for soft and LPS corals or tanks with live plants. A starting point would be about 1-3 watts per gallon of water.


 Fluorescent Bulb Sizes: You will see NO, VHO, and HO bulbs labeled as T-2, T-5, T-8, and T-12. The “T” value of a fluorescent light refers only to the diameter of the tube. T-2 bulbs are about 1/4″ (7mm) in diameter, T-5 bulbs are about 5/8″ (13mm) in diameter, T8 are 1″ (25mm), and T12 tubes are largest at 1.5″ (38mm). T12 are the bulbs that look most like what you commonly see office ceiling lights.



 Power Compact Fluorescent -PC 


Fluorescent Ballast Options: 

Ballasts used for these type bulbs are either coil and core ballasts or electronic ballasts. Coil and core are what commonly comes with NO and VHO strip lights. Coil and core are heavier, use more electricity, and produce some heat compared to electronic ballasts. Electronic ballasts initially cost more but their lighter weight and electricity savings offset this for many users. Some electronic ballasts are capable of powering NO, VHO, and power compact fluorescent (PC) in various combination.

Fluorescent Tube Color Options:

 There are many color spectrum available in fluorescent tubes, the most common used being full spectrum or daylight, actinic, and 50/50. Remember that the Kelvin rating used refers to color temperature and not the intensity of the bulb. A 20,000K bulb is more blue than a 10,000K bulb not twice as intense. A combination of bulb colors is commonly used to create the light spectrum needs of the tank.

Power Compact Flourescent 


  • Full Spectrum or Daylight Bulb: Generally a bulb of 6500K used to duplicate typical summer light. 5500K-6700K bulbs are a good spectrum for growing live plants. Some reef aquarists believe that corals look and grow best under light with a more blue coloration. A suggestion ratio is one or two daylight lamps for each 30 gallons of water

  • Actinic Bulb: A bulb that peaks in the 420 nanometer range and emits a fluorescent blue light that promotes the growth of the zooxanthellae algae found in photosynthetic corals and invertebrates; simulates dusk and dawn environment, and is used to accentuate the fluorescent colors of many corals and fish. This lighting is visibly blue and needs a full spectrum bulb to help offset the color distortion. Do this by adding a daylight bulb (around 5,000K-6,000K) to your lighting group but remember too much “daylight” (enhanced red spectrum = lower K value) can promote macro-algae growth. A suggested ratio is one actinic lamp for each 30 gallons of water.

  • 50/50 Bulb: These were developed specifically for marine and reef tanks to create light needed for the invertebrates in reef tanks and to enhance visual appeal. They have a daylight (6700-10,000K) and an actinic (03 blue) bulb in the same lamp.




Metal halides produce more lumens per watt than any other aquarium lighting source making them a popular lighting of choice for many reef aquarists. Metal halide lamps are more directional in nature with the most intense light found in the area located directly below the lamp and the amount decreasing with increased distance from the sides, front and rear. Metal halide lighting replicates the natural reflection effects of sunlight bouncing off surface water adding a “sparkle” effect. They do get extremely hot and because they are preferably placed 12″ above the tank they will require some type of ventilation or a chiller system, to dissipate the heat that will over-warm the tank water. A splash shield is also highly recommended as they can shatter if water gets on the bulb and you do not want glass and mercury in your tank!

They are composed of a metal halide lamp (bulb), ballast, lamp socket and mounting bracket, and a reflector. Reef aquarium metal halide bulbs are generally 10000K-20000K. They are either a single-ended screw type base or double-ended plug style, often called HQI bulbs. Both require specific ballast types for safe and proper operation. A general guide is one bulb for every two feet of tank length using 175 watt bulbs for tanks up to 22″ deep; 250 watt bulbs for tanks 22-28″400 watt bulbs for tanks deeper than 28″. The typical lifespan of a metal halide aquarium bulb is about 12 months. Bulbs are available in a range of wattage and color temperatures.

There are four types of ballasts commonly used: Probe Start, Pulse Start, and HQI Magnetic and are all bulb type specific magnetic ballasts plus electronic ballasts that can be used to drive any bulb type of the appropriate wattage.



This is the newest lighting source to come to use for the reef aquarium. These are low voltage, energy efficient, long lasting, and produce relatively little heat. and consists of small diodes attached to a circuit board. They are available in a wide range of colors allowing for combinations to create almost any desired spectrum; they create exceptional coral coloration. They are used for simulating moonlight or as primary or supplemental daylight spectrum. LED manufacturers are now creating fixtures with upwards of hundreds of LED diodes and adjust the diode color ratios to maximize nm peaks. Moonlight simulation is done with a small number of blue LED’s and placed on a timer; some aquarists are using a programmable timer to simulate a 28 day moon cycle. Options are expanding daily for all tank types.


 How long to leave the lights on depends on who’s home 

How long you leave the lights on depends on what is living in your tank andwhere; again a reason to research beforehand You want to closely mimic the native environment of the inhabitants. This is where timers can become your tank’s inhabitants best friend; a consistent lighting schedule will make everyone happier and healthier. A fish only tank can have lights on for as long as you like but most people seem to go with 4-8 hours per day. Tanks with live plants should have lights on for about 10-12 hours a day to give plenty of time for them to photosynthesize. Corals and reef tank inhabitants come from tropical regions where there is 8-12 hours of light a day.

The ideal lighting for a reef tank is very subjective in terms of type of lights, spectrum of lights, and how long to have each type on. There are a lot of ideas, theories, and opinions out there. Really, you need to start with the type of corals you want to keep, find out what they need, and build a lighting system from there. That said, here are some general guidelines:

  • A tank of mainly soft corals (mushrooms, leathers, and xenia) will likely do fine without investing in a metal halide system.

  • SPS corals (Monitipora, Hydnophora, Acropora, etc.) along with anemones and clams will need as much light as possible.

  • If you aren’t sure what types of corals you’ll end up keeping, to lean toward higher wattage fixtures so you can cover all needs.




What’s this going to cost to run?

What is your lighting system going to cost you (on your electric bill). Since everyone has different electric rates it is impossible to give an exact figure will cost to run. You can estimate the cost by taking the total wattage of the fixture (add up the wattage of the different bulbs), divide by 1000 to get the kWh of electricity used per hour. Multiply that by the number of hours the light is on in a day (8-12 hours per day in most cases) you will have your estimate per day. Another factor to add in to cost is the type of ballasts you use. Electronic ballasts can help reduce the electrical consumption of a lighting system compared to coil and core.

[ Total Wattage x Total Hours of Light ]     x      Cost per Kw (from your electric bill)       =       Daily Cost


For example: Your electricity costs $0.15 KWH and your system has 500 total watts and is on for 10 hours per day it will cost you about $0.75 per day or $22.50 per month (based on 30 days) to run that system.


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