Your lighting being too close and on too long is probably a big factor. I’d raise them up to 10-12” if you could and run the blues at 80 and whites at 20, following the coral labs program. It’s actually good. Also, I’d lessen the photoperiod to 8-10 hours too. You have them on so long at a constant intensity. What the others suggest is right too. Get more fish and feed more.