there's a big difference in "surviving" and "growing" bro. I feel that you are misleading with your statement. T5 CAN grow SPS, provided that you have a true High Output fixtures, no offence but screw the aquazonic or other lame ###### fixtures. Think ATI Powermodule or at least DE Lighting's HO fixtures.
48 watts of T5 in aquazonic fixture compared to HO fixtures like ATI is not enough to grow SPS, period. Unless one has a foot of water only and the fixture is directly above them corals.
Of those SUCCESSFUL sps reefers who uses T5 alone, 6 is the minimum i have seen so far. I have seen 8 and still needs supplementation from PAR38 LEDs (check out mengyang_neo and Bellinayu tank threads to know what i mean).
I have a 2 footer, total lighting power about 160w. I still feel it's not enough. Joe_P even recommends 250W mh for me!
My frag tank of 1.5ft meant for zoas only is using 2x24w.
Apologies if i offend you or anyone else, this is not my 2 cents worth, but a fact supported and displayed by many reefers both here and abroad.
Cheers!
Lighting, Water paramenters, Flow, 3 things paramount