Backyard Aquaponics
A place to discuss aquaponics

So, had a brain cramp yesterday and left my 1 RFF drain on and left the FH. Came back several hours later to find system drained down, RFF empty, both filters not working, or at least not flowing water. I have an autofill, but is couldn't keep up with an open 1" line discharging. The sump was below the pump intake and pump was not pumping. Luckily, after filling sump back up, the pump didn't burn up.

Here's the weird part: I measured Nitrites, which have been running between .25-.50+ for the last several weeks.
All tanks that I tested had the LOWEST nitrites that I've seen...almost all at zero or well below .25???
I did have some water that was added to the system when the autofill kicked on, but the Ft's were all not pumping when I got there. I was just wondering if I should shut the pump off for a short time and measure rates again?

It only logically makes sense that the water level had only just dropped below the intake and the new water lowered the nitrite rates. But, the water clarity didn't change much, and the ammonia did rise from zero to over .5.

Did you check the oxygen level in the filters when they had low water levels?

No, I didn't. The blower was still running, so I'm sure O2 levels were fine.

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Just wondering. If your auto fill was working, what was the effect on all the other water chemistry..
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PH was about the same. Ammonia was up, Nitrites were down. temp went down about 1 degree F.

Couple of possibilities -
1. Maybe the filters were working more like a trickling filter part of the time before they stopped flowing but I don't know if that's possible the way you have the system plumbed.

2. Might have developed some anoxic areas so the nitrites were given off as gas. This would depend on enough of the right types of bacteria being already in existence in the system.