Alkalinity keeps rising

[blkhawk10]

I'm thoroughly confused beyond belief at this point as to what the issue can possibly be. I do water changes bi-weekly with 9.2 dKH water and somehow my tanks dKH is 10.9 and two weeks ago it was 10.7 dKH. I don't add any additives other than amino acids on occasion. I assumed that doing water changes with lower alkalinity water would lower the alkalinity in the tank, I just don't get it! Can anyone help?

 

[chickenreef]

What's your ca and mg? If all three of those numbers aren't balanced then things will go out of whack.

 

[blkhawk10]

Calc is at 425 and Mag is 1260 which is a little low.

 

[reeftilldie]

has u recently changed salt mix? do u have corals in there?

 

[Randy Holmes-Farley Verified Community Expert]

Artificial rock and substantial drops in nitrate due to denitrification can both boost alkalinity. So can tap water.

Faulty test readings are also a possibility.

 

[blkhawk10]

No changes of salt...I've got six montis/digis, a birdsnest and an anacropora, not a lot for a 57 gallon...I have 2 other tanks I use the same saltwater on both have between 9 and 10 dKH.

 

[DBH2017]

What is your rock and substrate? Is it different than your other tanks? It may be buffering.

 

[blkhawk10]

It's all live rock with pink fiji live sand...this has happened before and it will get to a point where it starts going down again, it's weird I don't get it.

 

[Randy Holmes-Farley Verified Community Expert]

It's all live rock with pink fiji live sand...this has happened before and it will get to a point where it starts going down again, it's weird I don't get it.

As I mentioned, the choices are few. I'll list them in the order I think most likely:

1. Test error (including getting fine calcium carbonate particles into the test, giving a false high reading)
2. Additions that you are not are of, such as from tap water.
3. Additions from substantial nitrate declines via denitrification