Alkalinity keeps rising please help!

[Randy Holmes-Farley Verified Community Expert]

I am seeing this now did anyone solve the mystery

I don’t think there’s any mystery, just a known set of things that raise pH.

can you describe your situation?

Alk is measured how and changed how?
Nitrate rising or falling?

 

[Cary Meredith]

I don’t think there’s any mystery, just a known set of things that raise pH.

can you describe your situation?

Alk is measured how and changed how?
Nitrate rising or falling?

I have posted on other threads but hear is what is going on right now.

I had the neglected tank, Ammonia 0, Nitrites 0, Nitrates 0, ph 8.2, and Alk was over 283 ppm (15.8 dKH)

I have started doing water changes with Instant Ocean (had Red Sea) but trying to lower Alk so switched. Since Instant Ocean is still relatively high in Alk (I am measure at 11 dKH) when I first mix up a batch, I am lowering it to about 9 dKH using muriatic acid and then raising Ph back up to about 7.2 by agitating the surface water. I have done I think 3 water changes of about 30 gallons (total system water volume is about 280 gallons). I had the Alk down to about 259 ppm (14.48 dKH) , missed last weekend water change and just tested last night and Alk is about 270 ppm (15.094 dKH). Ph remains constant as I use a reverse lighting schedule on my refugium.

Testing Alk using Hanna checker.

I am not dosing anything right now as I am just working on stabilizing the Alk since it is so high.

 

[Rmckoy]

Hey everyone I am wondering if anyone could help me figure out why my alkalinity continues to rise on its own. I handy tested in a while and got a reading of 13.7dkh so I did a large water change and got it back down to 11.7 yesterday. Today it's back up to 12.04. I don't dose anything I have a 33 gallon with about 10+ gallons in the sump. I run a reef octopus 110, don't dose anything. Don't run carbon or gfo. Corrected if I'm wrong but isn't alk supposed to decrease over time instead of increase? Anyone have any suggestions?

I’ve had this issue with Hanna alk tester .
For the longest time if I didn’t shake the bottle of reagent well the bottom half would give low test results .
Lately and the final straw with this Hanna tester was extremely high results .
tried to confirm with salifert but salifert was normal at 7.5 where Hanna was reading closer to 9
I don’t want to assume but I think over time something happens with the tester to give abnormally high readings .
Could battery be the culprit ?
Following along to see what you find .

 

[Rmckoy]

I'm using a Hanna low range phosphate checker. And it may be a testing error but still, shouldn't my levels lower from reading to reading?

If the tester is giving off readings . Not necessarily accurate to be lower compared to yesterdays readings .

I am leaning towards testing error and blame it on the Hanna tester itself .
I have had the exact same issue and still can’t figure out why all
Of a sudden alk 9-10dkh when I’ve maintained 7.5dkh for 20 years .
Same salt the only thing that’s changed is what is trusted for testing results .

 

[Randy Holmes-Farley Verified Community Expert]

I'm not sure the 0.5 dKh rise is real, since it is within the uncertainty of the measurement, but these are the things that boost alk:

1. Topping off for evaporation with tap water or salt water.
2. Declining nitrate
3. Using tap water to make up new salt water
4. Artificial rock that is not fully cured
5. Slow dissolution of rock and sand due to low pH inside it when organics degrade to CO2
6. Many types of additives that may not sound like they contain alkalinity, or even claim they do not (falsely)