Funny in the states I had to work at getting tannins in my tanks, soaking leaves, loading tanks with driftwood, bags of peat, and even reusing old tea bags in HOB filter overflows.
Here I'm removing sticks, and branches, cutting back overhanging vegetation that drip tannins in the tank with the constant rain , and removing some of the aquaponics plants, because the tannins get so dark I can barely see the fish on cloudy days.
I had to do a 50% water change today just to dilute the tannins, even though nitrate is undetectable.
A surface shot after removing and replacing about 90 gallons.