ok ...I have found a few species of coral I'd like to try out ............BUT............absolutly every website i have found specifies "low" 'medium" "moderate" and "high" lighting depending on the type of coral of course......................so....................whats that mean in referance to wattage, for example if i put my PC lights on a fresh water tank....well thats pretty "high" lighting ....but i know I'm only putting about 4 1/2 watts per gallon into my tank with it....so what level is that?

also ......does the level change according to tank depth as well? i have always thought so...only because it seems logical that light in a 12 inch deep tank would be more intense than the same light in a 20 inch deep tank............no?

Snowboss

Depth makes a big difference as all wavelengths of light start to fall off as the water gets deeper and as they are falling all, there intensity and most imporantly, where photosynthetic corals are concerned, the photo active radiation reduces the deeper the light has to penetrate.

Watts per gallon is an obsolete formula when trying to apply to a coral reef. For example, consider all these light setups have the same Kelvin rating. A 65watt PC fixture will produce considerably less PAR(photo active radiation) than a 54watt T5 HO fixture and a 54w T5 HO with individual reflectors will produce considerably more PAR than the same T5 HO fixture that does not have individual reflectors.

Watt for watt, a single ended or double ended Metal Halide will produce more par than a T5 HO.

4.5 wpg of PC lighting is nothing compared to 4.5wpg of Halide when considering actual intensity and PAR. PAR is what corals that host Zooxanthalae need to live and grow.

PC lighting can be sufficient though, like you say, in a shallow tank or if the higher light demanding coral is kept closer to the top of the tank. You could easily keep mushrooms and Zoa's and some leathers. Some LPS like Torch or frogspawn could survive in that low a light. Just because a coral can survive, though, doesn't mean you could get good growth or even good coloration.

To answer your question simply, wattage per gallon is a useless reference to apply to photosynthetic coral.

Which coral are you interested in?

I understand completely your explination on the different intesities of lights not being dependant on wattage........thats why we took hundreds of metal halide fixtures out of gas station canopys and replaced them with much less wattage mercury vapor low consumption fixtures....saveing the station owners thousands per year and they got better quality lighting to boot....good post, Boss

A lot of people have kept coral like those under PC lights in a shallow tank but usually end up upgrading to a T5 HO fixture for better coloring and growth.

Also, the Blasto is an LPS so you would need to keep your calcium and alkalinity in the ranges more suited for stony corals. The calcium would need to stay in the 380-450 range and alkalinity in the 7-11dkh range.

i have duncans and a blasto with pc lights and they are both doing great, the duncans have little babies sprouting