Gareth, it's not just negatively charged particles that stay suspended. It's actually both neg and pos that keep bouncing off of each other and won't settle and play nice. Lime or gypsum act as a floculant to bind them together so they get heavy enough to settle to the bottom.

Have you done a jar test to see if it might be something else, something we call mechanical, that is causing the suspended junk?

It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.

Without a sense of urgency, Nothing ever gets done.

Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP Grandpa