I only use it when adding new fish/bioload to a tank to reduce the chance of an algae bloom . Not sure if it helps or not but I have some left over from removing tannins from a display tank so why not use it up. Never had any problems to think it's not working but I wouldn't use it all the time. Maybe in an african cichlid tank with fish only but it's just not needed in a planted setup.
I use a magnum in tank filter when I do need to use purigen/carbon for a short time.
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