Pond Boss Forums GENERAL QUESTIONS Muddy water One pond clear, other muddy

The 1/4 acre pond I had renovated last August, but not filled significantly until November, is amazingly clear, about 4 feet of visibility, easy. The small forage pond directly above it built November 24, stays muddy, with only about 4 inches visibility. After a big rain event, both are muddy, but the main pond clears up in a week or so, and the small one stays muddy. What could be the difference? Both were pump filled initially from the same creek. No alum was used in the main pond.

John, as you are finding out, no two ponds are the same, even if they are only feet apart. My guess would be the same problem that causes muddy water in ponds - an ionic imbalance.

Alum/hydrated lime should fix it. Do a jar test to be sure first.

The muddy minnow pond is only about 17,500 gallons, so shouldn't take over 12 pounds or so of alum to clear it under most conditions. I will try a bucket test. I have only been able to find alum in 4 pound bags. I have plenty of powdered lime.
Edit-I did the bucket test. Put in a half teaspoon of alum in a gallon. The clay clumped in about two minutes. Maybe too much alum?

I put four pounds of alum mixed with two pounds of quicklime in the minnow pond. No results. Then a few days later I put eight more pounds of alum and five pounds of quicklime slurry sprinkled over the surface. The visibility has gone from about four inches to about a foot in 24 hours. Should I expect it to continue to clear? When I stir up a little mud, it settles fairly quickly.

Well its the PH swing that really locks up the free clay. It will take much more product to coagulate the clay. Adding lime as everyone states will increase the EC of the water with less effect on clearing the water. If there are fish in the said pond they can handle the higher EC better then the PH swing.

It really is a catch 22. Yes adding the lime will keep fish alive but will cut the effectiveness of the alum in half.

Try this in a jar test you will see.

Cheers Don.

John, I'd suggest another 25 pounds of Alum and 12-15 pounds of hydrated Lime.

DonoBBD, I know we've debated what causes the floc before, but when the Alum and Hydrated lime are applied correctly and proportionately, there is no pH change whatsoever.

The floc of colloidal clay to alum/lime is ionic. Since colloidal clay is ionically negative, and both aluminum sulfate and calcium hydroxide are ionically positive, the hydrated lime enhances the positive charge of aluminum, not reduce it. Aluminum sulfate is a +3 ionic charge, calcium hydroxide is a +2 ionic charge, combined, +5 charge.

Rainman,
Thanks for your input.

That seems like a lot of alum for a 17,500 gallon forage pond. It's only available around here in 4 pound bags, at $5.50 a bag. The pond now has a foot of visibility, improved with the last treatment from four inches. A foot of visibility is probably good enough for raising Fatheads.

If the present weather pattern continues, all the ponds around here will be dry in a few months anyway. No significant rainfall since late December, and red flag fire watch daily. The spring fed creek now has insufficient water for pumping. I am afraid the south central states are headed for major drought.

Removing colloidal clay is not a partial, or cumulative, endeavor. If not clearing it all, it is a waste to put in at all. You could apply less, but as I said, Alum is not cumulative. Alum does not dissolve into the water, it sinks to the bottom, so applying a couple or a few pounds at a time is always like applying for the first time.

Alum, when countered with the proper amount of Hydrated Lime, is very safe. Aluminum does not dissolve in water above a pH of 5.4.

I believe that common alum (aluminum sulfate) is soluble (dissolves) in water, and therefore remains in the pond indefinitely.
https://en.wikipedia.org/wiki/Aluminium_sulfate

Aluminum sulfate is readily soluble in water. However, in the presence of calcium hydroxide (hydrated lime), it will rapidly precipitate as aluminum hydroxide and fall into the sediment. This precipitate will not form at acidic pH. Alum is acidic. So if you add too much unapposed alum, you can exhaust the buffering capacity of the body of water, causing a dangerous pH swing and leaving toxic soluble aluminum ions free in the water.

During floc treatment, positively charged, free aluminum ions will be briefly available to bind to negatively charged colloidal clay particles. This causes them to aggregate and drop to the bottom. As long as the pH remains high enough, excess aluminum not bound to suspended clay will also salt out very quickly.