Review on Seachem Purigen 100 ml Aquarium Fish Tank Filter Media - Ultimate Filtration Bag by Joey Makarovski

I have Fluval FX6, changed after 4 months. And you have a 46 gallon tank (which has half the water changed every 3 months. It has a selection of small freshwater fish. The tank has been installed for 8 years. They breed and I haven't had any new fish for 2 years Used years. Very small download for a Fluval FX4 I've had 18 months. So one day (suddenly) the water had a smoky appearance. I then changed half and then added a 100ml purigen sachet which looked ok. Good Seams, beige product and etc. (I used it successfully many years ago!) However, this time within 2-3 weeks everything in the aquarium, stones, castle, plastic plants etc. turned green with algae. 100+ very small snails (1/8") came out of nowhere. So I settled on a filter that was @ 4 months old. Everything inside was filled with heavy black algae. means saturation like a swamp! Also had a tan/dark beige one coating ung on all plastic parts did not react to bleach, not even regular bleach. It had to be rubbed by hand with a 3M plastic cleaning pad (yellow); nothing else would have worked! There was no detectable product in the Purigen pack I put in; it was still 100% intact. Instead, however, it was filled with black mold as if it had come out of a swamp! Before you say this is my fault for some reason; understand, this is how I have been caring for my tanks for a long 60 years. I've had all types of fish and aquariums, large and small, including saltwater. I never had anything but an ick and that was when I was a teenager. So far my life has been great for using all the media recommended by the manufacturers etc. can do some bad things to the biology of the tank. As a neuroscientist, I have no right to guess any more than I'm suggesting here. Opinions would be very welcome! Thank you for reading!