If your pond water is turning brown, there are two main reasons that commonly cause this. The first is a build-up of tannins in the water, and the second is excess sediment in your pond’s water. Occasional brown pond water shouldn’t cause any problems for your fish, but it does reduce the visual appeal of your pond. So what causes these problems and how can you fix them?

Tannins

If your pond water looks like tea, then this is most likely a buildup of tannins in the water. The majority of the times that people ask me about brown water, it is because of tannins in the water.

Tannins are a chemical in plants that cause them to turn brown. If you’ve ever made a cup of tea, you’ve seen first hand how tannic acid turns water brown. The reason your pond is turning brown is not that your neighbor decided to recreate the Boston Tea Party in your backyard, but instead, the culprits are the tree branches and leaves in your pond.

While it won’t necessarily harm your fish, excess tannins will lower the pH of your pond’s water. To keep your pond’s pH levels regulated, I recommend getting rid of the tannins in the water. Also, make sure to test your pH levels and adjust pH as necessary.

Sediment

If your pond water is brown and cloudy, then I believe there is excess sediment in your water. I like to test my water by scooping some into a glass jar and letting it sit for a bit. If there is a separation of water and dirt in the glass after 10 minutes, then I know my brown pond is from dirty water.

There are a few things that could be causing the sediment in your water. The first is usually from heavy rains. Rain will sometimes wash excess dirt into your pond, causing the brown, cloudy water. Another thing that could be happening is the fish in your pond are digging up the soil of your potted plants.

Steps to fix brown water

Once you find out what is causing your pond water to turn brown, then the next step is fixing the issue.

Fix sediment

To fix sediment buildup from heavy rains, try diverting the rainwater away from your pond. I think the best way to do this is by adding more rocks around your pond to build up a small embankment.

If your fish keep digging in your plant’s potting soil then I recommend you switch it up to something harder for fish to disturb. I like to use clay pond plant soil, such as Aquascape Pond Plant Potting Media. Then, add at least 2 inches of gravel over the potting soil. I would also suggest doing a water change of about 25% once a week for the next two weeks to help clear up the pond.

Fix tannins

To fix tannins in your water, you’ll need to remove the source of the problem and then perform a water change. Since tannins come from plants, I would start by removing all of the organic matter in your pond.

  1. This could take some work, but first, you need to scoop out all of the debris that has settled to the bottom, anything that is floating on the surface, and clean up any pond sludge. I recommend a good skimmer and pond vacuum to help you with this step.
  2. The next thing I recommend is a water change. Don’t go too crazy. A 25% water change should be more than enough to help clear up the water. I also recommend adding a water clarifier if you want to clear up the water faster.
  3. Finally, I suggest you try to prevent runoff and debris from causing future problems in your pond. Try redirecting rain runoff from flowing into your pond, since the water can collect tannins from the organic matter around your pond. I also recommend installing netting over your pond in the fall to prevent leaves from collecting in the water.

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