Review on AquaClear Quick Filter Refill Cartridge for Powerhead Attachment (A578) - 2-Pack - Enhanced SEO by Kim Norman

I use it with the AquaClear 70 and it does a great job of quickly filtering a 75 gallon tank in under an hour. I change it every time I change the water because that's when all the "stuff" rises and starts circulating. Trust me when I say this filter is white at first and quickly turns dark brown. That's how I know it works! I should probably replace this filter every few weeks instead of waiting for a monthly [yes right] water change. It would probably help a lot more.