Disappearing Nitrates

[jackleroy]

Hi everyone, I have a question about my nitrates disappearing.

I've been doing a fishless cycle on a 10 gallon tank since 11/1. It's going to be a quarantine tank, so there's nothing at all in it, just a filter, heater, and air stone.

I tested my parameters on 11/22 and my ammonia had gone from 4ppm to 0ppm. Nitrates were at 200 and nitrites were at 10.

I decided to add some freeze dried brine shrimp to see how fast the ammonia got processed. A test on 11/24 showed .5ppm ammonia, 200 nitrates and 10 nitrites.

I just tested again today on 12/6 and I got 4ppm ammonia, just 20 nitrates and 0 nitrite.

So my question is: where did my nitrates go? I tested a few times to make sure it's accurate. I haven't done any water changes at, just topped off the evaporation. There are no plants and I can't see any algae in the tank.

I feel like I can't trust the reading of 0 nitrites when the nitrates just disappeared like that, plus the ammonia is back up to 4ppm. What's going on?

Thanks in advance! I always get really helpful insight from you guys.

 

[AquaticMan26]

What kind of tests are you using?

 

[jackleroy]

API master test kit.

 

[bribo12]

High nitrites give a false reading on nitrates. Your nitrates were never that high but since you had a lot of nitrites it was messing up the test.

 

[jackleroy]

High nitrites give a false reading on nitrates. Your nitrates were never that high but since you had a lot of nitrites it was messing up the test.

Thanks! I didn't know that could happen, but it makes sense.