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BGA Battle

Robert Wrote:

> Date: Thu, 19 Oct 2000 01:00:10 -0400
> From: "Robert Sirota" <rob.sirota at aya_yale.edu>
> Subject: bga and post-erythromycin cloudiness
> Hello.  Here's a familiar situation with Bluegreen algae which has
> generated several interesting questions.
> I have a heavily planted 72 gal aquarium which is also heavily stocked
> with fish.  Rapidly growing BGA appeared about two months ago (rather out
> nowhere) and has covered certain parts of the gravel and plants, leaving
> other parts untouched (which is a peculiar, regularly commented upon
> phenomenon with this pest).  It was very fast -growing, so that no amount
> of "vacuuming" could keep up with it--it simply reappeared daily.  Water
> quality in the tank was fine-low phosphates, nitrates, etc. (There is a
> lot of material in the literature about this.  While bad water quality may
> lead to BGA outbreaks, in my view there is no degree of good water quality
> will make it go away, and it's appearance may have nothing to do with
> quality at all--as in my tank, which is a case in point.  Nor can plants
> outcompete it.  Nor is there any biologic cure for it which will not
> jeopardize the whole plant tank.)

I am beginning to believe that BGA is not driven by incorrect NO3 levels or
P overkill, but by accumulation of DOCs (Dissolved Organics). My conclusions
to this is because have been battling with BGA for several months now and
have a situation very similar to  Roberts: No measurable P, or NO3
"out-of-whack"  to drive the growth of the Algal/Bacteria. I too have a very
heavily populated tank (both fish and plants).

I was using H2O2 daily for a couple of weeks about a month ago, and although
I never eliminated it the BGA did knock it down to almost unseeable levels.
Plants also exploded in growth during this period, and one plant that I
could not grown (R. Macrandra) suddenly stopped melting and took off.

Then I went away for a couple of weeks (no H2O2 dosing). When I came back,
the BGA was voraciously back and growing as fast (daily) as I removed it
(and R. Macrandra started dissolving as soon as the BGA began taking off). I
believe the H202 is working not by oxidizing the BGA, but by oxidizing the
DOCs floating around in my tank, and maybe by increasing the re-dux (now I'm
stretching my knowledge).

So these are observations. I am now moving back to H2O2 on a daily basis
(small amounts folks) and I'll try this experiment again for repeatability.
If it works, I'll let you all know that my conclusions, although maybe not
scientifically correct, we're (or weren't) repeatable.

- Jeff

p.s., I'll be looking for some R. Macrandra again soon if this works Larry!