Dissolving Zoanthids

[Baldy]

I had never read about this until it just recently started happening to me. I had always read that zoas were a hardy, attractive coral to add to a reef tank. I couldnt agree more. I had 3 colonies of zoas, and 1 really nice colony of emerald palys. the palys hitch hiked on the live rock i bought, but the other 3 were frags that i added.

the frags had been in the tank for around 4 months, and the palys have been growing since i set the tank up in feb of this year. Until recently. Admittedly, i have been a bit negligent on my water change duties, but all parameters were still more than acceptable. 0 nitrates, 0 ammonia, 0 nitrites, 350 calc, 7 alk, 8ph, 80F temp. nothing went out of whack. I did a 20g WC 2 weeks ago, replaced the NPX bioplastics in my phosban reactor, and cleaned the skimmer, and since then, ive watched 2 zoa colonies dissolve, the 3rd which i was hopeful for is closing up and beginnig to fade now, as is the palys though to a lesser extent.

I dont necessarily need help regarding this as i doubt there is anything i can do, just wanted to share my disappointment. i have been very happy with my tank until now. kenya trees popping up all over the place, some rics that are splitting, hammer coral, along with some others which i havent been able to identify yet. other than a bad case of aiptasia that im working on, everything is great. i guess this is the downside to this hobby sometimes huh.