There is no end-all-be-all correct answer for you, and pay no attention to the Watts-Per-Gallon rule. Halides and T5 can generally throw the most PAR (Photosynthetically Available Radiation) compared to their Wattage. PC are typically the worst as far as PAR vs. Wattage.

That being said, that fixture is probably fine for you. You may not be able to keep some of the higher light-demanding SPS or clams on the sandbed, but by all means, you should be fine. There's some SPS that I wouldn't try, but for a long time, you'll have all the lighting that you need.


Seeing as your 55G is so narrow front-to-back, when you upgrade to a larger tank (oh you will ) you can use that fixture on your new tank and then put a couple HQI halides behind it or a couple T5 bulbs behind it.

Eric