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Re: Bluegreen algae control

>Date: Wed, 9 Jul 1997 17:44:30 -0500
>From: krombhol at felix_teclink.net (Paul Krombholz)
>Here are some non-antibiotic ways to control cyanobacteria.
>(1) I have seen many times that Ceratophyllum makes bluegreen algae go
>away.  It doesn't go away rapidly, but, as the Ceratophyllum grows, the
>bluegreens slowly diminish.  Hydrilla works the same way on bluegreens.
>Possibly we have allelochemicals here that inhibit the bluegreens.
>Ceratophyllum nor Hydirlla have any similar effect on green water,

I find that anacharis, and to a lesser degree, java fern also tend to repel
BGA.  OTOH, Hygrophila sp. don't seem to have any effect on it whatsoever.

>(2) Bluegreens have defensive chemicals of their own that can make them
>inedible for snails (pond snails and ramshorns) and algae-grazing fish.
>However, if the light is drastically reduced, the bluegreens become in
>three or four days much more palatable and snails begin to eagerly consume
>them.  I have a lot of windowsill cultures of aquatic plants in jars and
>some of them the bluegreens begin to take over and the snails refuse to
>them.  I take the cultures away from the windowsill and put them in the
>back of the room, and, after about 3 or 4 days, the snails begin to get
>active and eat the bluegreens.  In two or three weeks the snails multiply
>and clean up all the bluegreens.  I can then return the cultures to the
>windowsill and they will remain quite free of bluegreens for several

I also found that addition of ammonium tended to do something that made the
snails eat the bga.  It may have been ammonium, potassium, or calcium that
really did it, though, since I added all three at once.  Wherever I added
powdered limestone to the tank, the snails cleaned up the bga in that area
completely within a couple of days.

David W. Webb           Texas Instruments
(972) 575-3443 (voice)  http://www.dallas.net/~dwebb
(214) 581-2380 (pager)  2145812380 at alphapage_airtouch.com