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- Aug 14, 2016
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- Decatur, AL
Not sure how I missed this. Nice compilation!I've been doing a lot of research lately regarding QT and biodegradation of medications, and feel I now have enough information to start a thread on the subject. In short, I believe heterotrophic bacteria can build up in anaerobic regions of a long-term QT and eventually break down the medications we dose into the water. The sole exception to this is copper, which is not a true medication and thus cannot be biodegraded.
I first read about this here, regarding the degradation of formalin in saltwater: http://www.jzar.org/jzar/article/view/131
Next up is this, Praziquantel degradation in marine aquarium water: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4824874/
The study later discusses how microbial populations (bacteria, protists, algae, phytoplankton, cyanobacteria etc.) may be able to utilize prazi as an energy source after the first exposure to the drug. It also had this to say about the "Biofilm" in a marine aquarium:
A biofilm is any group of microorganisms which stick to each other and then adhere to a surface. Think bacteria sticking to the glass of a QT. Next up is this email exchange between @AlanM and employees of "The Seas", a Disney aquarium:
Conclusions: In light of this information, I feel it is unwise to maintain a long-term QT. Especially if you are using Prazipro, CP, metronidazole, antibiotics, etc. The concern here is that after awhile heterotrophic bacteria (and other biodegraders) will form a biofilm in the QT which will render the aforementioned treatments ineffective. This also explains why the use of medications in a DT environment (full of microbes) often fails, and why it is so important to only use meds in a sterile QT.
A practical solution to this problem is to periodically break down your QT, clean everything using vinegar and then allow to air dry thoroughly before reusing in order to sterilize.
Dosing chlorine, or one of the other chemicals mentioned, may eliminate some of the bacteria but NOTHING kills bacteria 100%. Unless you drain and allow to air dry thoroughly. That will sterilize only because you are (essentially) eliminating their environment.
For those who wish to disinfect using chlorine, here is a good dosing chart: http://dec.vermont.gov/sites/dec/files/dwgwp/DW/chlorinedosageemergencydisinfection.pdf
IME; it takes about a week to fully evaporate 10 ppm chlorine in a well circulated QT.