I've never used pre-filters until now and I've been working less at keeping canister filters clean. The pre-filter takes out a lot of waste before it enters the main filter therefore extending the life of the canister filter. The pre-filters as simple, quick and easy to clean. The pre-filter can be broken down, cleaned and re-installed in 10 minutes or less compared to 30 minute or longer it takes on the canister filter. The use of these pre-filters will save in time and money quickly. I buy one with every canister filter I purchase.
Eheim is excellent brand and they have very good quality products, i must have prefilters for all canister, saves time cleaning canister, and do not slow the water flow. requires monthly rinses....I highly recommend.