RE: [APD] An observation

["Jim Seidman" <js5 at seidman_net>]

George Booth, perhaps playing the troll, writes:
>Current aquatic lore holds that biofiltration is not as necessary in a
>planted tank as it is in a fish-only tank. Indeed, some authors go so far
>as to say that biofiltration is a bad thing and outcompetes the plants for
>critical ammonium. Everyone "knows" that plants prefer ammonium over
>nitrate since it takes less energy to use it.
>
>However, recent advances in nutrient management as promulgated by Tom Barr
>have shown that some level of nitrate (and phosphate) is good for plants
>and proper ratios of N and P are even bad for algae.
>
>While listening to Tom's Forum at the AGA 2K3 convention, I believe he
>also mentioned that algae can utilize ammonium very easily and that a
>dearth of ammonium may hold algae at bay.
>
>Hmmm, what better way is there to reduce ammonium and increase nitrate
>than biofiltration?

This argument makes the assumption that a lack of biological filtration will
somehow lead to high ammonium levels. In a well-planted tank, I can't see why
this would be true. In my filterless 125-gallon, I *never* reached a measurable
level of ammonium, even during the first week.

Research has shown that, at least for some species, ammonium is preferentially
used over nitrates. This means that if you're adding NO3, and it's being
consumed, your plants are probably already sucking up all of the NH4 that's
being produced.

How many tanks do you have that accumulate nitrates from fish wastes? That is,
do you have tank where you don't add any NO3 and the NO3 levels keep rising
anyway? If not, I imagine the ammonium is being dealt with just fine.

Unless the argument is that ammonium at levels that are undetectable by
hobbyist test kits still produce algae. I suppose one could make the argument
that a wet/dry would lower the undetectable levels even lower. However, this
would hardly make a noticeable different in nitrate levels.

>ASBESTOS_SUIT=ON

Keep the suit away from the tank, George. The fibers could clog your wet/dry
filter. :-)

- Jim Seidman



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