I'm having problems with several colonies of zoanthids that I cannot figure out. First off, my water parameters are all normal except nitrates might be a tad high at 40ppm. Lighting is 260w PC
on about 8 hours, and 250 watt MH
on about 2 hours a day on my 55 gal
. Fish, inverts and other corals are fine.
well, I have about 6-7 colonies or various zoanthids all on about 3-4 inch rocks. And I noticed couple colonies started shriveling over a period of couple weeks while still open. It starts with the base disappearing(the part that spreads across the rock), then the polyps disappearing. They still all open up but then the heads start disappearing.
I cannot figure it out, I tried moving them to different locations and they're still the same. I tried looking for nudibranches at night but didn't see any. I did an iodine dip but they're still disappearing.
My only guesses are maybe that nitrates are too high, too little water flow or too much lighting. Can too much lighting make the zoanthids die? or Are zoanthids supposed to be in direct flow of the pump for higher water movement? Or can I do a big water change like 60% to lower nitrates? I'd really appreciate any help! thanks