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Discussion Starter · #1 ·
Hi guys,

several days ago i made coil denitrator from a PET bottle with about 40 ft of airilne tubing classic size used in aquariums. As i didn't find BIO balls in shop, i just filled it with FLUVAL cottonwool which should as well serve as BIO media.

I tested today the output of denitrator using Tetra test for NO3 and NO2. What i was surpriced, NO3 shows extreme high levels already first seconds after adding 3rd substance. Usually it takes longer time to get red colour, so i assume NO3 levels are very high. NO2 also shown extreme high ppm - both over the scale.

Yesterday when testing i just found little bit higher nitrites - around 0.3-0.5 ppm and nitrates were same as in main tank.
What i changed since yesterday was flow of the water going to denitrator from appr 3 drops per second to only 1 drop per 1 or 2 seconds. I did so after reading some forums where guys suggested to decrease the flow during initial phase.

I got afraid if this doesnt mean H2S present in output. Otherwise i just don't understand such high levels of nitrates in output. They supposed to be same or lower. I understand this device is still just in initial period, so i didnt expect it to reduce nitrates, but to add ?? I tryed to smell the output line, if i can detect some rotten eggs, but i didnt noticed.

I was substantially changing water now almost every day about 10%, because nitrates keep to be high (50-75 ppm). I never had problem with higher nitrites, always showin at trace levels. This is due biological filtering. I also use CO2 injection and recently i let water get more oxygentated by airpump, because fishes tend to keep on the top and 'eating' air. Sorry for my bad english.

Please help
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