Check your pH, and alkalinity, through a water analysis lab. If your alkalinity is higher than 25 ppm, tannins from decaying leaves won't cause a problem. But, too many decaying leaves, or any other organic matter, can disrupt other aspects of water biology and chemistry. But, tannins won't be the source of a problem in hard water.


Teach a man to grow fish...
He can teach to catch fish...