ALK swings without livestock

[NorthernReefer]

I have set up my first tank and have an odd question. I tested my alk level when I mixed water Sunday. It was 8.1, today I tested it again and it had dropped to 6. The odd thing is that I don't have any livestock in the tank. It is still cycling. Is this usual? If not, what should I be doing to offset the issue. Thanks in advance for any information.

 

[Randy Holmes-Farley Verified Community Expert]

Rising nitrate will deplete alkalinity. So will precipitation of calcium carbonate.

Might also be test error.

 

[NorthernReefer]

Thank you.