Is this stable? Why is alk increasing?

[Benhuan]

Hi all,
Switched to Hanna all test (ppm) and my numbers are increasing without dosing. Got corals. Is it because my nitrates are dropping? Is this all considered stable if I factor error? Any advice will be greatly appreciated.
Thank you

 

[dwest]

Sorry I can’t read the numbers. But alkalinity can increase with water changes. Is that what you are experiencing?

 

[Benhuan]

Sorry I can’t read the numbers. But alkalinity can increase with water changes. Is that what you are experiencing?

I think If u click the photo it pops up and is clearer. I haven’t done a water change in about 2 weeks as I have no issues with nutrients. This is daily testing of all.

 

[dwest]

Yes, that worked. Sorry, its early

2 things come to mind. One is that those numbers are likely within the precision of the test kits. Additionally, alkalinity in my tank varies a lot throughout the day. So to see my alkalinity trends, I need to test at the same time each day. I don’t know if that is a big deal in your tank since you are not dosing though.

 

[Randy Holmes-Farley Verified Community Expert]

I agree that it is a small change and I'd just keep watching it to see if it is a real trend that keeps going up.

The rise in alk from nitrate dropping is 2.3 dKH per 50 ppm. If you really dropped nitrate by 8 ppm (as reported), then alk would rise by 0.37 dKH, or 7 ppm calcium carbonate equivalents.

You observed a rise of 8 ppm in alk, so it is not inconsistent, thought either or both measurements might easily be off by a large factor.