T5s are great but they cannot stand up to the look of zoanthids resting under MH 14 or 20K. You just won't get the brilliance of what theya re capable of.
Yes, they will look sweet under a good T5 array, but place them under MH and you will note a BIG difference.
NG, Mohawks, Raptors, Purple Hornets, just to name a few, under T5s are great, but NG, Mohawks, Raptors, Purple Hornets under MH 14Ks are stupendous.
I have placed the same zoas under T5s only and they dull to the same zoanthids under MH.
If you want a nice looking zoanthid with a lower cost electric bill go with T5s, but if you want zoanthids that POP and make you gasp, go with MH.