Tea Colored Pond Water
One by-product of having organic matter decomposing at the bottom of a pond is water discoloration. This is often referred to as tea colored water. The proper name is dissolved organic carbons, or more commonly known as DOCs. These DOCs make up tannins, which are natural pigments or stains found throughout nature. A cup of tea has its color because of DOCs. When you drop a bag of tea leaves into a cup of water, the cup of clear water starts changing into a darker color immediately. Just like with tea that has sat out for too long. water that is strongly stained with DOCs tends to be slightly acidic. This stain in the water is not a bad thing in and of itself, but it could be the tell-tale sign of a possible overload of the organic matter that causes the staining.
Another problem caused by excess organic matter is the depletion of oxygen. The process of leaves and other organic matter decomposing on the bottom of the pond can quickly consume valuable oxygen. This can be a potentially dangerous situation for any fish you may have, especially if the pump, which provides additional oxygen, shuts off leading to oxygen being sucked out of the water much faster. Excess organic matter is never a good thing to be sitting on the bottom of your pond.
This problem of overly saturated water with a decomposing pond bottom originally begins as leaves and other organic matter sink from the surface of the pond to the bottom, common during autumn, either by natural waterlogging or by mechanical filtration. Some pond systems use bottom style drains which create a suction to the bottom of the pond and exaggerate natural decomposition. The way to avoid this whole situation is by using a skimmer in the pond to pull leaves and other organic matter off the surface of the pond before it falls to the bottom. This system completely bypasses all of the problems above on a significant scale, and simply mimics natural waterways in nature that carry fallen organic matter further downstream. If it works for natural water systems, it’ll work for our ponds too!