"Organic breakdown" is just another way of saying ammonia. That is what the soil releases. As the tank cycles, it goes away, unless it continues to leech ammonia faster than the bacteria can colonize to convert it. Tea color is from tannin, which is non toxic and does not affect algae.
A normal nitrogen cycle takes 60 to 90 days. That's basic aquarium care.
With enough plant's that readily take up ammonia, and not too many fishes,,one could possibly never see ammonia level's rise and no harm to fishes .
Plenty of folks manage to stock a few fish in brand new, moderately planted, to heavily planted tank's successfully, and without harming fish/invert's.
Normal nitrogen cycle sans(without) plant's,,takes six to eight weeks rather than two or three month's.(For most folks)
Add some borrowed filter material from disease free existing tank (cycled) and this will reduce the time even further for bacterial colony to develop in proportions that would allow normal,sensible,stocking.
Have set up more classroom tank's than I have had birthday's.
Will be 56 years young next week.