Alkalinity Swing

[D_0827]

Historically my tank has had high alkalinity and low PH. 12Dkh/7.4PH.

Recently and I think after dosing bright well aquatics Koralle VM and Replenish my corals weren’t looking so great.
My Duncan Coral speaks for the whole tank so I knew something wasn’t right.
When I tested the water my alkalinity what I believe is a large swing and now my alkalinity is at 10DKH.

Chalice coral started melting away and my torch is now not looking so great.
Any suggestions, can this be a cause of alkalinity alone? What should my next steps be?

I’m attaching some tests for reference.

 

[goosemans]

It depends how long it took for alkalinity to drop. Meaning did it drop that much in 2 min or 2-3 days. I’d be more concerned with that low of pH. Corals and fish will not survive long term. Do you run power heads or a protein skimmer?

 

[goosemans]

Also possible you overdosed trace elements to dangerous levels

 

[D_0827]

It depends how long it took for alkalinity to drop. Meaning did it drop that much in 2 min or 2-3 days. I’d be more concerned with that low of pH. Corals and fish will not survive long term. Do you run power heads or a protein skimmer?

Tests are about 2 weeks apart each. And yes the PH has always been a concern for me. I run a protein skimmer. The only time I’ve ever been able to increase is when I religiously open windows in the apartment on the weekends, which isn’t always possible.

 

[goosemans]

try running a CO2 scrubber attacked to your skimmer intake. Should help a lot

 

[Randy Holmes-Farley Verified Community Expert]

I would not trust a pH reading in tank water that had to travel to a store for analysis. PH 7.4 is unlikely accurate for the tank pH, and is a serious issue if it is.

 

[D_0827]

I would not trust a pH reading in tank water that had to travel to a store for analysis. PH 7.4 is unlikely accurate for the tank pH, and is a serious issue if it is.

Yeah I’ve been told that it might be an inaccurate reading although I’ve gone to various places and they have given similar readings. Before the alkalinity went down my corals were growing and looked great.

 

[Randy Holmes-Farley Verified Community Expert]

Yeah I’ve been told that it might be an inaccurate reading although I’ve gone to various places and they have given similar readings. Before the alkalinity went down my corals were growing and looked great.

Having a closed sample will generally lower pH as bacteria continue to produce CO2 in it. It doesn’t mean an error, it means a transit difficulty in maintaining the original pH.