watts per gallon isnt a truly accurate way to mearusre lighting at all. 110 watts with a good reflector or separate relfectors for hte bulbs is a whole different animal then 110 watts with a poor relflector. I think this is where people are giving advice without know what the deal is. And pressurized co2 makes a world of difference. moderate lighting with press co2 will grow almost anything, just more slowly. However high lighting plus excel or diy co2 will almost always cause algae disaster or take up all your time mixing yeast bottles. 2 watts per gallon of pc light with AH supply lighting + press co2 will def grow almost anything and fairly well.I've said this before, but I grew some of my nicest Rotala macrandra and Pogostemon stellatus with 136 of T-8 (96w, 9325K) and T-12 (40w, 5500K? Nutrigrow) lighting. I did have pressurized CO2 which was a big help. Algae was practically non existent and P. stellatus rarely if ever stunted. The plants grew much slower with that amount of light, but so did the algae.
Why is it that such high light levels are recommended and do we really need it for most plants?