Green Hydnophora issue

[iceman86]

i know there are a few people on here with these corals so mabye i can get some help. When i bought it, it had amazing polyp extension. it was fuzzy all around and it slowly went down from there in the course of a month. The only polyp extension i get now is mostly on the tips and it isnt much either. The coral has already doubled in size since i got it a few months ago so i dont think its in danger. I know they like a lot of flow so i put a powerhead pointing right at it and it didnt change anyhing.

My water parameters are also good. Everything in the tank is healthy and grows at a really fast rate.

Any ideas?