I have been doing research for upgrading the light on my 56gal from low light to medium light. The tank dememtions in inches are 30L×18D×24H, but let's exclude 4 inches from the hight because of substrate and say 20. That would mean the tank is 10,800 square inches, so that would equal about 7 square meters. I was thinking of using 6500k cfl bulbs. So I looked up PAR ratings for cfls and found a chart that shows a 23watt cfl at 20in away from the substrate at about 34 PAR. So I am assuming that in this instance each watt is roughly 1.5 PAR. Therefore if I used cfls that are 65watt (250watt equivalent) they would be 97.5 PAR each. Now let's say I use 3 bulbs, 97.5 × 3 = 292.5 PAR, and now divide 292.5 by our 7 square meters to equal about 42 PAR per square meter. How does this look? Is all my math correct? It will not have pressurized co2 (yet) but I will be adding excel, so is it possible that this is too much light? I really don't want to have an algae problem. Thx all in advance!