i've kept a grey/greenish one and also a dull lime yellow carpet (s. haddoni ), in a 18"d x 18" w / dsb under six 48" 32 watt zoo med t8's for a few years before trading them in . they grew from 4" & 5" to more than 18" . would not have kept a bright neon green or blue one under that lighting , i'm told they're collected in shallow water . s. haddoni anemones are also found in deeper water , some will do well in lower light levels such as those that are acceptable for bta's . you would need to get more lights but (unless your tank is rather deep and or in a dark room), don't need a kilowatt of high intensity discharge bulbs , vho , ho , pc or ho t5's to keep them . the watts/gallon rule is too generalized (watts are a measurement based on generated heat not light), depth of tank output of bulbs , reflector material and ambient light level of the room are factors not accounted for . a good way to do it would be to find out the lux/lum output of your bulbs and shoot for 13,000-15,000 over your anemone . good luck