Who Gives A Fish Forums

Could be a combo of things. Low nutrients, light stress, or even pests. Have you checked for flatworms or AEFW? Those little buggers will suck the life out of Acros. A quick dip might reveal something. Also, how's your carbon use? Too much can strip colors.

I'm new to SPS, but my LFS said flow is key. I have two MP40s on my 120-gallon, and my Acros are coloring up nicely. Maybe add another powerhead? Also, what's your photoperiod? Too much light can bleach them.

My Montipora faded when I overdid water changes. Maybe cut back to 10% weekly instead of 20%? Also, are you dosing anything? Too much of one thing can throw off balance.

I've heard UV sterilizers can help with color. Anyone try that? My tank's too small for one, but I'm curious.