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RE: "overfiltered"

James Purchase said 

"No matter how much volume (or area) your bio-filter has, you will NEVER
have more bacteria in it than is necessary for the amount of ammonia and
other waste products being pumped through it."

I am familiar with the dynamics of biofilms. But reading the following I
still have the impression that some believe it *is* possible to have too
much biofiltration, and that with less there are benefits for the plants.
What also perplexes me is that if I were to reduce my biofiltration
capacity and lower my fish load there would be less fish food being
introduced, less fish waste, and a new bacterial equilibrium. It seems a
steady state will always be reached unless there is a considerable
reduction in good colonization sites in the filter-- in other words not to
have "just the right amount" of bacteria, but to ensure conditions that
permit less.

Roger Miller said (in separate posts and in cases where the fish load
permits):

"Avoiding bacterial filters gives a simpler, less expesive and usually
quieter setup. REDUCING THE COMPETITION FOR AMMONIA SHOULD (ALL ELSE BEING
EQUAL) PRODUCE BETTER PLANT GROWTH"

"THE END PRODUCT FROM REMOVING BACTERIAL FILTRATION SHOULD BE HEALTHIER
PLANTS, less noise from the machinery and less work for the aquarist."
[emphasis mine]

Diana Walstad, in her book, says 

"And the fact that nitrates accumulate in your tanks does not mean that
your plants are not taking up ammonium. The plants are predictably ignoring
the less desirable nitrates as they compete with the filter bacteria for
the ammonium. Only by measuring ammonia levels (not nitrates) as your
gradually reduced biological filtration could you determine how much
nitrification is really necessary for the fish load in your tanks.
   The relatively rapid nitrate accumulation in your tanks may be more a
function of the heavy biological filtration than the heavy fish load. Your
plants would probably remove more total N and prevent nitrate accumulation
if you didn't have the trickle filters. This is because plants may
accumulate more N in their tissue when it is given to them as ammonium than
when it is given to them as nitrate.
    In my planted tanks I have been surprised at how little biological
filtration is actually required. WHEN I DECREASED BIOLOGICAL FILTRATION (BY
REMOVING THE FILTER MEDIA IN THE CANISTER FILTERS), I HAD FEW PROBLEMS WITH
NITRATE ACCUMULATION AND WATER ACIDIFICATION.
    Although nitrification is essential in tanks without plants, it is much
less important in planted tanks. My point is not to advocate dispensing
with filters altogether, but I would urge readers to believe in their
plants more than trickle filters.   [emphasis mine]

I am almost certain I am overfiltered if you mean colonization potential in
my  canister and the biomedia there. I am not certain that the plants that
my plant growth would improve by reducing it. So regardless of the
particular nitrate dynamics in my tank and setting aside questions of
expense and noise, can we be overfiltered from the plants' point of view?

BTW, Eheim Pro canisters are completely silent :)

Jared



___________________________________________________________
Jared Weinberger                    jweinberger at knology_net  
______    http://www.knology.net/~jweinberger/     ________