Agreed with what was just said. Tannins don't harm the fish at all, just turns the water yellow and eventually brown.
Some people recommend soaking the wood for 2 weeks before putting it in the tank to help with removing the tannins or boiling it in a pot for an hour. I did the boil method and as most people would tell you, it didn't help as much as we hoped haha.
The tannins will go away eventually, and purigen is not 'necessary', but if you didn't want your water color to be yellow or brown, this is a good fix.
Here are before and after photos using purigen, the 2nd photo is ONLY 5 hour after I put it in. On average it takes about 24 hours to clear up the tank.
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