Zoa melting/recession

kiswanson · May 8, 2022

I have a 45 gallon e170 Red Sea max AIO and I’ve had a separate rock island for zoas since I set things up about 11 months ago.

today I was noticing that a number of the colonies in the middle are gone or severely retracted.

salinity 35.1, nitrates 33, phosphate .66, dKh 8.5, ph around 7.7-8, ca 450, mag 1470. I do dose all 4 reef, NoPoX, live phytoplankton and Red Sea energy ab+, and some iodine (due to being low on Icp testing about two month ago). Also dose MB7. None of that is particularly new. Rest of the tank looks good.

there is one or two aiptasia, but that also isn’t new, I spot treat them with aiptasia x every so often abs have a file Fish. Also, where the aiptasia is, its next To happy looking zoas. I didn’t see any obvious posts moving around, but I’ll have to look closer. I haven’t added any new zoas for a long time

any thoughts would

full tank shot for reference of how the rest of the tank looks

kiswanson · May 8, 2022

here’s the zoas rock from a few weeks to give context if where it is in the tank. I did not notice any issues with them at that time

kriskool123 · May 8, 2022

I notice that my zoas like good amount of flow. Usually whenever mine close it’s either time for a water change or most of the times it’s the flow decreasing because the pumps need to be cleaned

kiswanson · May 11, 2022

My zoas rock, previously covered by good looking zoas, melted back and receded really significantly over the course of a week. All the rest of the coral (sps, lps, softies) and my BTA and clams look great

After doing a water change, changing carbon, moving the zoa rock away from a toadstool leather that was coming somewhat close, and looking to see any evidence of file Fish, emerald crab, or peppermint shrimp going near the zoas (none that I saw) and finding nothing but a few asterinas (which may just be around eating tissue of spray dead/dying zoas), I decided to dip the rock.

I did a coral Rx dip (4 capfuls per gallon x 10 min), rinse, lugols iodine dip (brightwell 40 drops per gallon x 10 minutes), rinse, soak in fresh saltwater with basting, additional rinse, then back in the tank.

This was in the water after the coral Rx rinse - amphipods and a few asterina starfish. I personally didn’t see any spiders or nudibranchs.

Hopefully it helps