take picture of it to identify the type of algea. there are different treatments. It sounds like youre doing A LoT in that tank to combat HA...maybe your corals are stressed from the GFO, Algea ridX, Biopellets...etc. I know when I treated my dads tank with biopelets for his HA the corals did suffer tissue recession but thats my experience with them. BTW they did the trick and in a few mths the tank had no HA after being overrun with it. Is there a way to relocate the corals to a holding tank, then treat the current 90g tank for your HA or briopsis, then return the corals. Even a small tank would give you a chance to nurse the corals back to health with good water quality and spot feeding.