thank you, I don't know the fixture has no markings, I bought it several years ago and don't remember, there was no booklet with the fixture when I bought it, and I actually used it for freshwater at the time, to replace the lighting that came with the tank. Yes it is a standard 55 gallon tank. I guess I'll have to find out as things progress. I may, later on, just replace the fixture altogether just to be safe. Then add corals.Hey TD,
Reflectors play a huge part in how effective T5's are. What fixture are you using? Is the tank a standard 55g (48*13*21?)?