Pond Boss Magazine: Clearing Muddy Water

You built a small pond, huh? Sweet! You did your homework, figured out where the water would come from, hired the earthmover who did his magic by rearranging a bunch of dirt, you did a rain dance, and now you’re ready to make it look fantastic and grow a few fish for fun. You’ve spent time smoothing the shorelines, seeding your favorite grasses, and the fish truck will be in town in no time.

There’s just one little problem you didn’t quite expect.

Your newest favorite fishing hole appears nothing more than a mud hole right now. A color somewhere between chocolate milk and a rusty nail isn’t quite what you wanted.

But, it’s a new pond and several people told you it’s likely to settle out and clear up on its own. But, what if it doesn’t? Should you go ahead and do something now?

Sure, it’s only been full for less than a month, but you can’t see much difference in clarity after that month.

What’s the smartest decision?

Do some homework.

Get a gallon jar, preferably glass, so you can see through it.

Fill it with pond water and set on a shelf in your garage. Give it a few days and see if clay is beginning to fall out and layer the bottom. If clarity begins to increase, odds of the pond clearing on its own increase.

Think about it this way. For most situations, good clay is needed for a pond to hold water. The reason clay compacts so well is because its particles are so small. Look at sand for comparison. A particle of sand is much larger—you can see the grains of sand. But, you can’t compact sand. Build a dam from sand and expect seepage—lots of seepage. The best clay particles are microscopic. They are so small that they bind, and with moisture, they’ll bond and minimize seepage. That’s why the best pond builders look for clay at every potential pond site.

But, here’s the catch. Clay can be so tiny it’s actually lighter than water. Suspended clay particles are usually the problem that causes muddy water. When fresh water rolls across disturbed soils, expect it to pick up whatever is in its path. In the case of different metals and minerals, they’ll dissolve. In clay’s case, it suspends.

In order for the pond to change into that greenish color we all seem to like, that clay has to sink. But, if those particles are lighter than water, they may need a nudge. Think about a feather floating in the air. At some point, it has to drop, unless the wind keeps blowing. But, pitch a ball bearing into the wind and see how long it takes to bop you on the head. Not long. See clay the same way. If clay particles in your pond are heavier, they’ll sink quickly. If not, it may take a month or more. If they are really small, they may never sink, and your pond won’t clear up.

While you wait, be sure to vegetate disturbed soils above the water line. If you don’t, and that’s the source of your muddiness, expect the next rain to send more clay into your pond.

To help make your decision whether to amend the water or not, do some homework. There are several traditional ways to clear muddy water. The old timers used to tell folks to add some hay, which will attract the clay and clear up the pond. If you want to contend with rotting hay, go for it. But, there are no assurances the water will clear, and then you have a bale of waterlogged hay. Maybe so, maybe no? Depending on the ionic charge balance of your water, (Really Lusk, ionic charge balance?), you might do some good with aglime. Charge balance can be determined through a basic water chemistry analysis. If you have more negatively charged ions compared to positively charged ones, that might be the problem. If so, adding aglime can help balance the charges, causing a release of clay to settle to the bottom.

But, what most professionals do to speed up the process is to look at gypsum (Calcium sulfate) or Alum (Aluminum sulfate) to do the deed. Both of those products cause microscopic clay particles to become magnetically attracted to each other. When they attract, their weight increases, and they become heavy enough to hold hands and sink.

How do you figure that out? It’s not hard.

Remember that gallon glass jar? Get three more of those for a total of four. Fill them with pond water. In Jar 1, add a teaspoon of gypsum. For this test, buy gypsum at most garden stores. If you need to use gypsum in a pond, buy it bulk. Stir the gypsum into Jar 1 until totally mixed. Then, take two tablespoons of water from Jar One, and mix into Jar Two. Mix four into Jar Three and six into Jar Four. See which one settles. If they all settle, then extrapolate how much gypsum you’ll need to clear the water. To make it simpler, weigh the teaspoon of gypsum. That will help you figure out how much gypsum you’ll need. Yes, there’s some math involved, and you’ll have to use a scale for weighing. But, what won’t we do for our ponds, right?

If the gypsum doesn’t do the trick, set up the same experiment and use alum. But, everyone needs to understand this key point. When alum is used, you need to know what you are doing. Once you hit the break point with alum, the pH of your water will rapidly change. Fish can die from that.

Understanding the cause of your water’s muddiness goes a long way toward clearing it up. Look at the neighbor’s ponds. If those are clear, odds are yours will be, too. If ponds around you are turbid, chances are yours will be as well.

Can you prevent a pond from becoming muddy? Maybe. As the earthmover finishes the job, bring in some gypsum, and top all the disturbed soils with it. As soon as the heavy equipment is gone, get some grass growing in the freshly moved dirt, especially above the waterline, into the watershed, and even along the course where water will flow into the pond.

Can you clear the water and keep it that way? Maybe. I’ve seen it go both ways. We’ve cleared muddy ponds that are still beautiful after twenty years. Others, two weeks after clearing them, a rain pushed them back like they were. People had to treat them again. Big watersheds for smaller ponds perpetuate the issue by changing the charge balance of that pond.

There’s those words again, charge balance.