Feb 27, 2003, 8:22 PM
Post #184 of 312
Re: [SMW1] High Nitrates Level? Try This!
[In reply to]
I just signed up today after all these years in the fishy (but not Koi) hobby, so I hope I don't upset too many people by digging this thread up again!
Although I'm not into Koi much myself (my sis was a Koi breeder, though), perhaps I could throw some light onto why a TT works so well for removal of NH3, NO2 AND NO3, even though it's NOT supposed to work for NO3s. Why?
Basically, the nitrification potential of any biological filter depends on how much well-oxygenated water passes through a huge amount of filter media like bio-balls. BUT, the DE-nitrification potential to breakdown NO3 to N2 gas simply cannot be achieved in the same environment, since the denitrif. bact. are essentially anaerobic in nature.
And yes, I too am mostly into coral reef tanks nowadays, where NO3 was also a major problem for us, but not any more. When we used TTs in our marine tanks, NH3 and NO2 would drop super-fast, but NO3 would slowly climb, and climb, thus requiring monthly water changes just for the purpose of lowering the NO3 levels to below 20 ppm. Of course we use other methods nowadays to keep our NO3 levels to 0 ppm ALL the time, but these methods wouldn't work in a Koi pond, IMHO.
Coming back to the TT filter, I have a feeling it works for you guys because the key word here is "TALL". In a tall TT, the water entering the filter has lots of O2. But as it drips thru' the bioballs, the O2 is used up by the aerobic bacteria to break down NH3 and NO2. As the water continues flowing down, O2 levels are being depleted which would then enable the denitrif. bacteria to start growing more and more. This would then seem like the top portion of the TT would be the nitrif. part and the bottom, the denitrif. part. This could be why a short but wide surface area TT wouldn't be as effective.
This can be confirmed if someone has an ORP (redox potential) monitor that measures the readings at the point of entry, and the point of exit. If my guess is correct, there should be huge difference in the 2 readings.