<a href=showthread.php?s=&postid=12165264#post12165264 target=_blank>Originally posted</a> by miwoodar
Apparently someone in this thread on RC was supposed to tell us how to determine dosages to target the growth of relavent baterial populations...hmmm?
ideally, the alcohol or sugar should be dosed directly into the localized anoxic environments where denitrification is occurring. in large aquariums like the Montreal Biodome, they dose methanol directly into their denitrification coil. this permits only the denitrifiers to exploit the extra carbon, rather than boosting the total overall population of bacteria in the system. dosing the entire system makes for a nutrient free-for-all, and passive diffusion/bernoulli limitations in aquaria (meaning sandbed, live rock) means the anoxic environments don't get first hit at the extra carbon. it is possible they won't get much boost at all when the depletion of nutrients in substrate is factored in with lower diffusion of water.
as for the quantity, you need to titrate the nitrates. this is because the C:N ratio has to be stoichiometrically favorable for efficient denitrification, with C being carbon, and N being nitrogenous compounds, in this case nitrate. if the ratio is imbalanced you'll get blooms of non-denitrifying bacteria. a good C:N ratio for efficient denitrification is between 3.5 and 5, for those willing to calculate molar concentrations.
Dosage must be empirically determined by titration of nitrates, i.e. start off with very, very low levels of alcohol while measuring nitrates. As the dosage of alcohol increases, nitrates should begin to fall. When 0 nitrates are achieved, the correct dosage has been attained. Do not dose extra, and do not dose if no nitrates are detectable to begin with.
other considerations:
Low frequent doses are preferable to high infrequent doses. An ideal regimen would entail constant dosing of low concentrations of alcohol.
Localization of alcohol with denitrifying populations. Dose as close as possible the environment of denitrifying bacteria. Extra unused alcohol will be consumed by something else in the tank, and lead to a bloom of undesirables.
Purity: reagent grade alcohols are preferable to pharmaceutical grades, which are preferable to alcohols bottled for human consumption.
<a href=showthread.php?s=&postid=12165264#post12165264 target=_blank>Originally posted</a> by miwoodar
Maybe you could enlighten us a little, Mr. Anderson?
!!!