Alkalinity raising on its own???

[Coral55]

My alk has raised from 8.5 to 9.8 on its own I’m about 2 weeks. no water changes or dosing during that period until today which dropped it back to 9.3. I’m using the Hanna checker and even bought new reagent to make sure it wasn’t that. I also tested with Red Sea and got the same results. 30 gallon tank with a few sps. Calcium was a little high(525) and nitrates are 0 with a 1.025 salinity . I don’t want nitrates at zero and was curious if that has anything to do with it? New to posting on here but follow the forums. Any info would be greatly appreciated! Thanks

 

[Auquanut]

Welcome to R2R. The only thing I can think of that would increase alk is your top off water. Are you topping off with RO/DI? How old is the tank?

 

[Randy Holmes-Farley Verified Community Expert]

Might your top off water have alk in it?

Assuming not, If nitrate was not substantially higher and the drop raised alk, then it is likely test error. Alk does not just rise on its own.

 

[Coral55]

Yes Ro/di reading zero on the tds. Tank has been running about 15 months. I have 2 other tanks running for 2 1/2 years and don’t have this problem at all.

 

[Coral55]

Might your top off water have alk in it?

Assuming not, If nitrate was not substantially higher and the drop raised alk, then it is likely test error. Alk does not just rise on its own.

I will clean my top off tank out good and see if that is the problem. possibly some salt water can get into it when I pull the filters out the sump if I don’t have the lid on. Will get some new test vials also since they are getting old and used a lot. Thanks for the info

 

[Perry]

I have had the same issue, mine would rise from 7.5 to 8.5 in one week. Could be ph suppression, a CO2 Scrubber may help. FWIW, I have an aio setup.

 

[Randy Holmes-Farley Verified Community Expert]

I have had the same issue, mine would rise from 7.5 to 8.5 in one week. Could be ph suppression, a CO2 Scrubber may help. FWIW, I have an aio setup.

What is pH suppression that would lead to alk rising on its own? A CO2 scrubber will raise pH but does not directly impact alkalinity.

 

[Coral55]

Might your top off water have alk in it?

Assuming not, If nitrate was not substantially higher and the drop raised alk, then it is likely test error. Alk does not just rise on its own.

Update. Tested/cleaned top off tank and ro and everything was good. Since water change Sunday the alk again has gone from 9.3 to 9.8 in 5 days. LFS tested water for me today to make sure it wasn’t an error on my part. They read exact same as my tests. How is this even possible?? Is a ghost dosing my tank? Haha

 

[Sailfinguy21]

Doesnt alk go up if magnesium goes up or calcium goes down ?

 

[Beats001]

Did you figure this out?
I am facing the same thing.
My alk is rising without dosing or water change, also not my rodi, its strange. I have recently been dosing dsr phosophate reducer which contains iron and my nitrates have decreased as well as my phosophate, it must all be connected in some manner.