Good activated carbon will remove the tannins, but I make no promises on the quantity required. It takes a lot of carbon to clear a lot of tannins. Water changes are cheaper IME.
Well water tapped from a deep or fractured stone aquifer can be just as high in gases, expecially CO2, as a community system.
Well water tapped from a deep or fractured stone aquifer can be just as high in gases, expecially CO2, as a community system.