To grow, sps
need enough light and enough calcium, alk
. If you get the right amount of these they will grow. I'd say your downfall here is the light. I had the same as you and it wasn't enough for my acro and it turned brown. For a birdsnest and Monti it may be enough light to keep it alive but the growth will be slow. Have you check your calcium? If your other coral are taking it out of the water and its low your sps
wont be able to absorb any and grow. LPS
like frogspawn are totally fine under T5s and if your LPS
are growing they are using calcium from the water....