I have cichlid that are pretty messy. They produce a lot of waste and I was having to clean my filters weekly. I added these pre-filters and now I can go 2 to 3 weeks with just cleaning the pre-filters weekly. It takes me about 10 minutes to clean the little filter and get it back into service not the 30 - 45 minutes the big filter takes. Very good investment
Keeps my canister filters cleaner longer. Whenever I do a water change (generally every 2 weeks), I clean the reusable sponges as well. I haven't even needed to open my canister filters for 3 months now! Another innovative and well-made product from Eheim.