Trying to stay away from the Aluminum and it's side effects.
What side effects? None known I am aware of. The only "myth" I have ever even heard of was a long since and repeatedly debunked claim of a link to Alzheimer's.
Cottonseed hulls and some other ionically positive charged organics, like Barley straw, can
sometimes work, but also add MASSIVE amounts of biological waste (detritus) to the pond that would normally take years to accumulate.
Alum and Hydrated Lime, applied properly are entirely safe and have no known dangers or residual problems....it's (in one form or another) in most all municipalities drinking water and countless canned vegetables.
