**Update**
I read from another site to feed less powder coral food to keep white hydroids in check. To test, I took a frag out and manually removed as much hydroids I can from a frag. I than started feeding my fishes frozen only, and stopped feeding coral frenzy. Crossing my fingers, but after a week the frag that I manually removed hydroids from, didn't have that many hydroids regrown. Gonna manually remove hydroids from the other frags soon, and update this thread.