The Spring Filter Cartridges are designed to only trap larger debris and let fine debris pass through to prevent the cartridges from being clogged as quickly when the pool is especially dirty, like when you open the pool in spring.
EZ Test Pools stays current on tech, is a vast resource of knowledge, and goes out of their way to ensure customer support/satisfaction. I was receiving misinformation from other pool companies and the manufacture of a product. I became frustrated and Robert did not waiver on his advice or give up on me. As a result, I did not buy a high ticket item other pool companies incorrectly stated were necessary and the manufacture corrected its unethical stance. EZ Test Pool Supplies is a rare bred and has earned my customer loyalty over surfing to save a few bucks.
I love this filter for my Oasis Z5 and E-Z had it for the best price. This filter clears out a lot of debris (dust, sand, worms, leaves). I rinse it out every time to make sure the dirt does not get caked onto the filters. If you let the dirt remain after a cycle of cleaning and don't get to it the next day or two the filters will stain and may get clogged.