Is your pond beginning to look like the Boston Harbor of 1773 – you know, the color of British tea?
Tea party popularity was resurrected this year by the fickle human race, but are the fish with that trend?
Tannins, or plant polyphenols, released by decaying organic matter in the water, cause this coloration, often described as tea colored. It is actually very clean and usually clear, like looking through amber colored sunglasses.
Historically, sailors would travel from the ocean up a waterway until they reached salt free tannic water or “black water”. This was more desirable than simply reaching salt free water, because the tannins (akin to tannic acid) helped keep the water good for drinking, probably by keeping undesirable bacteria at bay. Photo at right shows tannic water entering ocean.
In a fish pond, too many tannins might lower the pH a bit, but is actually a healthy environment for most fish. Aesthetically, many consider it a problem. If so, try keeping leaves and other organic debris out of the pond, as the best prevention. Good aeration also helps, as does carbon filtration (see blog-Aeration Tips & Tricks). There are a multitude of water treatments available to help “whiten” the water.
For more on tannic water and tips on treatments and adjusting ph, check out these web sites (photo of scuba diver in Florida spring with tannic water drifting in):