Backyard Aquaponics
A place to discuss aquaponics

So it read 2ppm the other day & now it has shot back up? .Try with a different test kit,maybe you have sorted it,now the foam has gone & it's just a faulty test.You'll be able to rule it out & then this mystery chemical might be the answer.Like you said,8ppm would kill everything.

No issue with temp swings, heated greenhouse keeps water 81-83 degrees. I cannot speak as to the quality of fish food as I did not acquire it, but the fish seem to eat it and it keeps my nitrates in the ideal 120ish range so I will stick with it for the moment. Unfortunately I seem to have lost my helper yesterday, warden wanted to fire him for whatever reason, now I have to find a new helper and teach him the art of aquaponics and hydroponics. This is critical to my success as I do not have a chance to access the system every day and depend heavily on my helper to feed the fish and check water quality. Finding a prisoner with adequate knowledge of water chemistry is harder then you would think, most of these guys never finished high school.

When you get readings "off the chart"

To get a more accurate reading

Dilute your test sample with water say 10% water from fish tank and 90% water and retest different mixes to get a reading in the middle of the colour chart

I know this is old now,but just interested to know what's happening?.Did you get it sorted? or at least find out what the problem was?