I have recently added a large stump of wood to my tank 180 litres / 47 gallons and my water is stained Heavily with tannins, I wouldn’t mind a small amount of staining but the light is barely reaching the plants. I’ve been running around 500g /18oz of activated Carbon for 3 days yet it still has not cleared the tannins out of the water to any noticeable degree , does anyone have any experience with removing tannins ?