Zoas not opening, Duncan closed

[Tom-nanoreef]

I have been having issues with corals in my 16 gallon nano tank and I am not sure why. This is my first tank and I recently added 4 new corals last week. For the first 1-3 days, my 2 Zoas were opening up almost completely without too many problems, however, they stopped opening about 2-3 days after and have not opened fully since. I just did a full test test yesterday and parameters are good, I had to add a lot of magnesium and calcium supplements due to low magnesium and calcium levels. I did a few big water changes and had to increase temperature from 23 degrees celcius to 25. Now my tank parameters have been good for the past couple days. I don’t really have any problems with my candy cane it seems. My Duncan stopped opening yesterday and his tentacles have visibly shriveled up since I got him. I am suspecting too much light but I am not sure since I do not have much experience. I am planning on lowering light to 7 hours. However, I am worried about stressing the corals any further. My invertebrates have all been happy and don’t seem to be having any issues.

Tank parameters -

Ammonia - 0 ppm
Nitrite - 0 ppm
Nitrate - 5 ppm
Magnesium - 1400
Calcium - 400
Alkalinity - 12
Salinity - 1.025
Temperature - 25 Celsius
Lights - Coralife Biocube size 14 lid, 10 hours
Ph - 8.2

This is what my coral looks like now. Pictures of them being open are from last week.

 

[Reefin Aint Easy]

What were the parameters before you dosing? You mentioned you had to dose a lot to raise your parameters. Trying to see how much and how fast you raised those parameters as well as you doing large water changes. It"s all a big shock to the tank/corals.

 

[Tom-nanoreef]

Calcium was 360 and magnesium was 950

 

[MaxTremors]

IMO, you don’t have enough corals that you need to be dosing anything (plus they’re new and not acclimated to your tank, which means they aren’t growing), water changes should be completely adequate to keep your parameters in check. The stock lights in the biocube are not too much (especially the 16g), I would be running them with both channels (white and blue) at full intensity for 10-12 hours a day. If anything they may be inadequate. I think the issue is that you’re dosing stuff which is causing instability. Being slightly out of range is better than dosing a bunch of stuff and causing big swings in your parameters. What salt are you using? Your Alk being 12 is okay, but you don’t have any wiggle room on the upper end, so be very careful dosing any Alk supplements. I would suggest switching to a salt that is 8-9dkh (Fritz, coralife, Red Sea, are few off the top of my head that mix around 8-9). There’s no real benefit to running your Alk that high other than slightly faster stony coral growth, but in a 16g, faster growth isn’t necessarily a good thing. I would just stop dosing anything, do weekly water changes with RODI (and maybe a lower Alk salt), and just monitor your levels, stability is more important that chasing specific numbers.

 

[rhostam]

Agree, the big swings probably ticked them off. A few days isn’t enough data to call something stable. Zoas will recover, just give them time. I’ve read that duncans are good indicators of water quality and will react readily to big charges or deteriorating conditions. I have found this to be true anecdotally.

 

[Tom-nanoreef]

I usually use saltwater from my local fish store for water changes, my alkalinity has always ran pretty high like that. I have red sea salt that I have yet to use. Thank you for the advice.