Candy Cane receding

gabom234 · Feb 16, 2025

My 35 gallon waterbox has now been running for around 8 months. I have had a candy cane coral in the tank for 6 months and it had been looking great for many many months. As of maybe a month ago, it started alternating between looking nice and puffy, and looking generally shrunken and ugly. I started noticing this interesting growth at the base of it, I assumed it was possibly growing a new head, but today I noticed it looks like the flesh is starting to recede at the base as well. Any ideas as to what may be going on? I must also mention that a lot of my corals are looking a bit off color and closing up a bit. This happened to me a month or two ago, and I think it might have been due to a random snail die off event, because after I fished it out, all the coral recovered well. I noticed this morning I may have hermit crab or cerith snail that has died in one of the caves, so I'm wondering if this is causing some of the corals to become irritated. My parameters have been relatively stable: Salinity 1.025, temp 78, nitrates around 11-14, alkalinity went from 7 to around 9 since I stated dosing around 2 or 3 weeks ago, and my phosphates seem to be an issue. They have been 0 since the inception of the tank, maybe 3 or 4 weeks ago I took out a bag of carbon with gfo that I had since the beginning in an attempt to get them up a bit, and Friday when I checked it was .23 which is a pretty big change from 0 the previous week. I wish I would have retested that same day to make sure it was a good reading, but I did not. I did a 20% water change yesterday, and retested today and got 0.06 for the phosphates. I'm not sure what other relevant information might be useful, but I look forward to any help.

Edit: That circular thing right in the middle is the growth I was referring to. Any insight on that is appreciated.

Shirak · Feb 16, 2025

No idea what thing you are looking at in the picture. Photo with white lights is a must.. I do see the tissue recession. No I don't think it has anything to do with a snail dying.. or hermit. A snail dying in a 35gal system shouldn't cause much of a blip.
Parameters relatively stable but yet they don't seem to be. Alk 7-9 over a few weeks, phosphate 0 then .23 then .06 I agree 0 is bad but so are wild swings. Aim to keep it between .05-.1ppm Alk going from 7 to 9 could be an issue. Why did you decide to go to 9?

gabom234 · Feb 17, 2025

It's hard to get all of the information down in one post, so I will try to clarify. I've only started to have these parameter swings in the past 3 weeks or so. For the first 7 months of the tank, parameters have been stable. Alkalinity started off around 8.5, and had slowly been dropping over a period of months. It got to the point where it was hovering around low 7s, so I posted on here, and was given the advice by Randy Holmes-Farley to start dosing once it got under 7. I tested at 7 about three weeks ago, so I started dosing soda ash. My intention was to get it to 8.5 over the span of two weeks, and I accidentally got it to 9 instead. I do not plan on continuing to raise it beyond that, since I have heard that is an ok number. I have had phosphates at 0, literally the entire time I have had the tank. I never had any algae issues, my tank has been flawless until recently as well. I have been meticulous in my weekly testing and water changes, but for some unknown reason, I started getting strange algae growing. Again, I posted on here for advice, and was told that 0 phosphates was a problem and to eliminate the GFO by Randy(I had been using Chemi-pure Elite since tank inception based on the LFS recommendation when I started). The phosphates went from 0 to .23 in one week, and back down to 0.06 from one day to the next after a water change. I understand that those swings are not good, but of course it is not at all what I was shooting for when I made those changes. I find it difficult to take decent pictures, but here are some better ones.

Shirak · Feb 17, 2025

The corals can get phosphate through food. Having some in the water is a buffer. I think once you get the Alk stabilized where you want it and the PO4 at some range where it might swing a little either way, the corals will settle back down. The spot you circled hard to tell.. looks like candy cane flesh? Maybe it is trying to grow a new head there?