Who Gives A Fish Forums

Thanks for the advice, everyone. I'll try raising nitrates slightly and check my alk stability. My dKH is at 8.5, but I'll monitor it more closely. Lights are about a year old, so maybe it's time for a spectrum check.

I've noticed my Acropora and Montipora are losing their vibrant colors. My tank is a 75-gallon mixed reef with Radion XR15 lights, running at 60% intensity for 10 hours. Parameters are stable: 8.1 pH, 1.025 salinity, 0 nitrates, 0 phosphates, 420 calcium, 1300 magnesium. Any ideas what's causing this?