How many watts per gallon

[jdfenn]

hey guys

I have been researching the whole metal hallide situation all weekend and it seems that the kelvin level is mainly for looks. There is a common noiton that blue light makes corals grow faster but it seems that it is not true. My question is how many watts per gallon do you guys have for a tank that is giong to grow SPS at there best but also have some LPS corals and also some softies.

thanks alot

[Poseidon]

I wouldn't use the old Watts per gallon rating anymore. thats an OLD LFS standard.

Heres an example, a tank that is 8 in deep by 24 in wide by 72 in long is approx 60 gallons. So is a tank that is 24in deep and 8 in wide and 72in long.

Obviously in the second scenario the light intensity is much less at the bottom of the second tank then it is in the first. And under the watts per gallon rule you would end up with the same wattage for both tanks.

I would go more with this, a 250W MH bulb is good to a depth of about 24" any hting deeper then that needs 400W.

Also know that each MH bulb can light an area 2' by 2' so a 6 ft tank ideally will use 3 bulbs for even light.

When you are talking about NO, VHO, or PC it gets a little more complex. But the general consesus is SPS and clams do BEST under MH. SOfties and LPS do fine under VHO and PC and NO is best used for fish only...

Remember light falls off as the square of the distance, so light is 4 times brighter when you cut the distance in half. Or to double the distance reduces intensty to 25% of what is was.

Hope this helps, Mike

[Onthefly]

Jd - Poseidon hit the nail on the head with regard to the WPG rule.....

My experience, I set up a 5.5 ga nano with 64W power compacts (13W Ac03 and 51W 6500K)...that equals 11.6WPG!!!! Even with that, even with my acros 3" from the light, they faded and/or browned badly. By friday of this week, I'll have my 10K 70W MH set up and the before and after pics should be striking!

HTH

[jdfenn]

I have been doing alot of reading and alot of talking to my teachers here at K.U. and it seems that they all have some advise to what lighting to use. Here is the most important thing that I have learned. The wavelenght, the kelvins, combine to be important for coral growth. Hence it is important, IMO, to have various wave lengths. As 6500K bulbs produce yellow oranges and browns, these are good for yellow orange and brown corals. 10,000K produces blue, it is good for blue corals, and 20,000 K are good for vilet corals.

Even with this info I am going to run 2 400 watt xm 20,000K bulbs, 1 250 watt 10,000 k bulb, 4 6 watt PC, and 4 vho bulbs above my 120g tank so that I can cover the bases

[apophis924]

Jdfenn, I am was under the impression that pigments reflect wavelenghts of light that THye do not use. Chlorophyll reflects green because that wavelength is not used in photosynthesis. Your bright colored corals and even animals in mid to deep water are those colors because those colors are invisble at the depths they inhabit. Below a certain depth red/orange and even browns are invisble since those wavelength do not penetrate that deep. A coral that grows in blue light will not be blue in color. That would indicate that the coral's pigments are reflecting blue and not absorbing it. Your bright orange corals use blue light because they abosorb it and not orange. If you put a coral and or plant in the wavelagnth that is the same color of that planet it will die. Plants/corals reflect colors they do not use to produce food , the wavelengths required for photosyntheses are abosorbed which is why we do not see them. Of course when dealing with living systems there are ALWAYS excpetions to the rule.

[kevinpo]

Photosynthetic corals contain an algae in their cells called zooxanthellae these are all brown. The corals can regulate their numbers and receive nourishment from them. They turn darker brown in low light conditions and lighter in highlight conditions, which can affect/tint the corals color. Pigmentation in corals can be used to reflect light to enhance adsorption or to reduce adsorption (this is especially true in fluorescing pigments in the placement either above or below the zooxanthellae).

The genetic makeup of the coral also affects the coloration. Two of the same species coral placed side by side will be totally different colors both in the wild and in the home aquarium. Alkalinity and nutrient levels also play a part in coloration. There are still many questions to be answered in the area of coral coloration and the role it plays in the health of the corals.

In addition most corals capture live prey (zooplankton), which can also have an effect on their coloration.

Different Kelvin lamps also have different PAR ratings and even two lamps of the same Kelvin but different wattage will drastically change the color of corals as will distance of the coral from the light source. To make matters worse corals often go through a acclimation period lasting up to 6 months when lighting conditions change (even when changing out old bulbs for new ones of the same wattage and Kelvin). They often turn brown during this period.

IMO/IME it is best to move the coral to different locations until you achieve the coloration you prefer and then hope it stays that color.

Regards,
Kevin
PS: Here are a few links to articles you might find useful by proffesionals rather than my ranting
http://www.aquarium.net/0998/0998_4.shtml
http://www.aquarium.net/0597/0597_2.shtml

[apophis924]

IMO/IME it is best to move the coral to different locations until you achieve the coloration you prefer and then hope it stays that color.

Kevin: THAT Statement is most likley most useful information anyone can pass on about this Hobby. Between advertising, So called experts and all the science. I to have found that experience and diligent observation is the best way to keep a reef system looking at its best. Be it lighting, water quality or filtration methods. Since my Corals dont read they dont want to follow the "text book" paramters set by the experts in the industry. This is a truely live and learn endevor.