We have a pond that has many oak and other trees near by. The water has...

Asked August 27, 2013, 10:32 PM EDT

We have a pond that has many oak and other trees near by. The water has become very dark in color. I assume the color is due to tannic acid. Will this condition harm the fish and other organisms in the pond? What is the lowest Ph level recommended for keeping the fish healthy? What corrective measures would be recommended?

Trumbull County Ohio recreational pond management water quality

1 Response

Greetings anonymous,

Quite likely tannins, but a number of other factors can also cause dark-colored water. Is it still translucent (like coffee or tea) or opaque (like coffee with milk)? Was the onset of the color sudden or has it been accumulating or present for some time?

The tolerance of pH levels varies with different species of fish and other organisms. In general, low to mid 6s to mid to high 7s are fine for most things. There is plenty of variability in what becomes harmful or even toxic, and different biological activities can be affected differently. Is you pH low enough that you feel corrective measures may be necessary?

Please feel free to contact me directly if it would be useful to discuss details in person.

Best,