i have 3x39 watts of t5ho on my 35g tank (3 foot by 12x17high)
i compared it to a 175w mh lit similar sized tank, and the mh was a lot dimmer than the t5ho (3x39) with proper reflectors. also, the t5 will not heat the water like the MH, nor use as much electricity, nor need to be changed as often as the mh bulb.. on a small tank like that, mh isnt the best option. and i keep sps, lps, softies, and a clam....