Originally Posted By: Greg Grimes
Is it possible for the alum to bind to bottom clay or simply not have enough charge to be "pulled" into the water to bind with suspended clay????


Greg,

The alum will bind a little, but the bottom mud can't contain a higher alum concentration than the pond water. That would break Fick's law, which states that molecules quickly travel from areas of highest concentration to areas of lowest concentration until balanced.

I've noticed that pre-dissolving and spreading the alum can quickly settle suspended clay, temporarily clearing the water. It looks very impressive. However, as wind and fish stir up more fine clay particles, it will once again go into suspension. If the water has a high enough concentration of alum (in combination with other positively charged chemicals), you can stir up clay all you want to, and it will soon re-settle. Most pond water (especially in old ponds) has enough calcium, magnesium, salt, etc. that it doesn't take a lot of alum to settle it.

Some ponds are almost pure rain water, and it takes a lot of chemicals to saturate it enough to occupy the negative ions.
That's why a dosage of alum that clears up 1 pond often doesn't clear up another.

Last edited by bobad; 07/22/09 02:47 PM.
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