Whats wrong with my efflo ??

[Aquattro]

If it were mine, I'd do a reasonable(not too big) water change and replace the bulbs. Make sure there is no direct flow hitting it. Probably not the crabs.

Ca and alk levels would help too

[FWC]

Ya ,I have hanna testers for alk and Ca ,but I don't really have the RO water to use with them

However a water and bulb change are quite do-able.

Its not under direct flow ,and has done quite well and the spot until now ,so I'm stumped as to what it might be.

[Aquattro]

I have a coral that would fade over a couple of days when the bulbs needed changing. Could be that. Start there, see if it helps. Don't over expose it, and don't change too much water, the coral is compromised, so nothing drastic