SPS Recession / Tissue loss from base - any ideas?

[hometown9]

All of my SPS seem to be doing the same thing - receding from the base. No issues for a year and this happened in the past 2 months. No real change in levels, except my Alk started going down (consistently from 8 to 6-7). Everything else in the tank is ok - montis, LPS, etc. Button seems a bit weak though. My Mg seems a bit off the charts

Salinity - 1.026
PO4: .25
NO3: 5
Calc: 440
kdh: 7
Mg: 1600

Any ideas? Thanks.

 

[Nick30G]

That alk swing from 8 to 7 or 6 dkh is a big swing. Whys its going down like that if your dosing I assume?

 

[hometown9]

3+ month ago, the Alk was ~7 and I would dose to bring it back up to 8'ish. In the past couple of months, that number would drop to 6'ish, and I would dose the same amount to get it only to about 7. I wouldn't think a swing of 1-2 would have that much of an effect, but maybe it does?

 

[hometown9]

How fortuitous. My ICP test results came back just now. Here they are - salt and RODI. Wonder if nickel could be the problem?

 

[ReefGeezer]

3+ month ago, the Alk was ~7 and I would dose to bring it back up to 8'ish. In the past couple of months, that number would drop to 6'ish, and I would dose the same amount to get it only to about 7. I wouldn't think a swing of 1-2 would have that much of an effect, but maybe it does?

It does for SPS corals, particularly if the change occurs quickly or often. If you want to keep SPS, keep the swings less than 1 dKh per day. Don't let it fall too low. If it does, raise it slo-o-o-o-wly.

 

[hometown9]

It does for SPS corals, particularly if the change occurs quickly or often. If you want to keep SPS, keep the swings less than 1 dKh per day. Don't let it fall too low. If it does, raise it slo-o-o-o-wly.

What about white-band disease? Is this a possibility? My ICP test actually showed decent results so not sure it's chemistry.

 

[Duffer]

Alk swing is what is causing this. Stability is the king of reef tanks. sometimes the slightest alk swing can hammer a coral,especially acro's

 

[ReefGeezer]

What about white-band disease? Is this a possibility? My ICP test actually showed decent results so not sure it's chemistry.

In my opinion, it's probably alk swings. Your corals have started using more calcium & alk and whatever you have been doing isn't keeping up. This is cause 1 for troubleshooting SPS issues. My advice would be to fix the alk instability first, then worry about chemistry or disease if that doesn't help in a month of so. What do you dose to maintain the alkalinity? How often? Etc.?

 

[LobsterOfJustice]

Could be a lot of things. Alk swings as mentioned. Or flow or shading/light. Make sure you’re powerheads don’t need to be cleaned. Are you using LEDs? Maybe consider adding some T5 supplements. Was going to also suggest an ICP test. Anything out of the ordinary on that should be addressed.