TetraWhisper Bio-Bag Filter Aquarium Cartridges, Medium Filter for Freshwater and Marine Fish, Removes Odors and Discoloration, Ready to Use Medium Green Filter

I’ve got a 3.6 gallon tank! (Probably could utilize the SMALL size option better!). Works excellent! Delivered fast!

These charcoal filters do what they say they will! They catch so much nasty gunk from our 5 gallon tank. Sometimes, I can rinse them, and get an extra week out of it, but they get regularly changed, every 3-5 weeks.

Have been using this forever. It does a good job at filtering out the icks -- just wish it could filter out green algae that seems to have taken over the tank after 15 years. Easy to change the bags and add in the charcoal. Our fish are happy!

Very easy to change!!!

while the product is great, and keeps my tank clean, it doesn’t seem to last as long as it says it should. i find myself replacing them every 2-3 weeks rather than a month. the cartridges are easy to install - just simply rinse in water and place into the filter. however the filter does a great job collecting all of the debris in the tank and my fish are healthy, so i can’t really complain.

These are perfect for my fish tank. It keeps the tank crystal clear.

Your tank shouldn't be without these filters.

Nice item, happy with purchase.