> >The person who mentioned that to me didn't know how the alum would =
> >prevent algae growth, so I thought someone on the list might be able to =
> >explain it. I presume that the aluminum would bond with the phospohates =
> >making them unavailable to algae, but I honestly have no real idea. And =
> >if alum prevents algae in lakes, could we use it in our tanks as well?
> I haven't heard anything about alum, but I use chelated iron as a phosphate precipitator. The Dupla Fe drops really help in this area.
Alum is a flocculant. It causes the algae to clump and sink. It is
commonly used for this purpose in water treatment. It may have an side
effect on phosphate concentration, something easily enough measured....
but I have not looked into that.