Muddy water treatment calculator

Treat on a calm day and spread the product evenly over the whole surface, dissolved or mixed into a slurry where you can. Do not treat when the fish are stressed or oxygen is low. Alum only settles the clay for good if you fix where it comes from, because bare banks, livestock, a feeder stream or bottom-feeding fish will muddy the water again.

One milligram per litre across one acre-foot of water weighs 2.72 lb. Without a jar test the calculator uses the extension ranges: alum 25 to 50 lb per acre-foot, gypsum 500 to 1,000 lb per acre-foot. Alum works at a fraction of the dose because it flocculates the clay rather than just settling it, but it also pulls pH down. When total alkalinity is under 50 ppm, add hydrated lime at half the alum weight at the same time to hold pH. If you leave alkalinity blank, the calculator assumes the buffer is needed. Gypsum is slower and you need far more of it, but it does not change the pH.

Jar test: fill a jar with pond water, add a small measured amount of product (a fraction of a gram per quart), stir, and wait an hour. Repeat with more or less until you find the smallest dose that clears the water, then enter that weight and the jar volume. The calculator scales it to the pond by the acre-foot. A jar test replaces the guess, and the ranges are only a starting point.

Sources: extension muddy pond sheets from Auburn University and Oklahoma State University. Practitioner discussion: Pond Boss forum threads Alum Kicks Clay Butt and Alum kicks clay's butt again.