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Re: [APD] An observation

I am (er, was) one of those people that George referred to when he said that
"Indeed, some authors go so far as to say that biofiltration is a bad thing
and outcompetes the plants for critical ammonium."  I believed so firmly that
biofiltration was unnecessary that I removed it from all six of my planted
aquariums, setting them up with only powerheads for circulation.  The first
time I did it I careful measured ammonia levels on a daily basis and gradually
reduced the test frequency over a period of a couple weeks.  I never once saw
ammonia appear in that tank.

I kept all of my tanks that way for a couple years.  Plants flourished.  Fish
(nothing fancy) flourished.  *Usually* algae did not.  While algae was usually
in control there were.. umm.. "events".  Most of the events were green water
problems, which cropped up in my largest tank with any small provocation.  But
I also had occasional problems with various sorts of attached algae that would
appear, overwhelm a plant or a tank then disappear again.  I lost nice carpet
of glossostigma that way.

I finally went back to mechanical filtration on all tanks because I was tired
of suffering the 24-48 hours it took for water to clear after even minor
disturbances.  When I did that, the algae "events" ceased.  That could have
been an effect from mechanical filtration, but a mechanical filter left in
place for more than a few hours is also a biological filter, so where should I
place the credit?

I still think that a filterless setup is a great system for a low-tech planted
tank -- a tank that you want to set up and leave undisturbed for ever and
ever.  If you're going to do anything to the tank, like prune, aquascape, add
fish etc, etc then biological filtration is needed to get a tank over the bumps.

Do you need to go to the length of setting up a big wet-dry filter on your
planted tank?  I don't know.  Tom Barr provided evidence that green water and
other algae "blooms" can be triggered by ammonia spikes.  An extension of that
reasoning is that the bigger and badder your biological filter is, the less
likely you are to have those algae spikes.

I don't know if this principle extends to algae problems other than "spikes."
 Does using a big biological filter reduce algae problems?  I'm not interested
in whether algae problems come or go when different sorts of filters are added
to a tank.  I am curious whether anyone has run two setups that are identical
in lighting, feeding, fish and plants populations but differ in their bio
filtration.  If so, was there a difference in the kind or severity of algae
problem in the two tanks?

Roger Miller    
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