Air collar makes smaller bubbles for improved performance Easy Flow accessory increases water circulation Coarse, anti-clogging sponge Weighted base sinks instantly and helps prevent floating Sponge filters offer reliability and hassle-free operation. With no moving parts, all you need is an air pump with some airline tubing, and you've got a filter that is fully contained within your aquarium.  Sponge filters are completely reusable, don't need any replacement cartridges, and last for several years. Plus, they are gentle enough for betta fish, baby fry, shrimp, and other slow-moving species. Trusted by fish farms and wholesalers, they are an excellent choice for aquarium filtration that you can set and forget. To optimize the sponge filter’s performance, we’ve included an air collar that replaces the need for an air stone and minimizes bubbles coming out of the side of the sponge. The air collar produces smaller bubbles that lessen noise and create more continuous current. If you need greater water circulation, use the included Easy Flow accessory that curves the uplift tube so that water flows out of the sponge filter horizontally across the water surface and around the aquarium. The Aquarium Co-Op sponge filter is designed using coarse foam so that it can go many weeks between cleanings. The weighted base will immediately sink to the bottom of your aquarium, so no more floating up after a water change or initial installation. Also, the green plastic helps hide algae and blend in with your live aquarium plants. Height of Sponge Filters  Item Height with Easy Flow Nano sponge filter 11–21 inches Small sponge filter 10–20 inches Medium sponge filter 12–22 inches Large sponge filter 12–22 inches Recommended Sizing Chart Aquarium Size Sponge Filter Size Fitment Small column (or narrow) tanks Nano Trim the tube heights to shorten if needed 5.5-gallon tank (and other tanks shorter than 10") Small Trim the tube heights to shorten if needed 10-gallon tank Small 20-gallon high tank Medium 20-gallon long tank Small 29-gallon tank Medium 30-gallon tank Medium 40-gallon breeder tank 2 Medium 55-gallon tank 2 Medium 75- and 90-gallon tanks 2 Medium (for planted tanks) or 2 Large (for heavily stocked tanks) 125-gallon tank 2 Large Tanks deeper than 22" Medium or Large (2 or more) Stack the sponge filters to increase height Additional Supplies Needed The sponge filter cannot produce air on its own, so you also need to buy the following components to run the sponge filter:— Air pump — Airline tubing— Check valve (to prevent water from pouring out of the tank when the power is off Pore Size: 25ppi (different manufacturers rate porosity slightly different as it's an approximation) Installation Instructions: Read this article with step-by-step instructions   Cleaning Instructions: 1. Use a fish bag, ziplock bag, or pitcher to put around the sponge while inside of the aquarium. 2. Lift the water and sponge out to catch the majority of debris that will come off while removing. 3. Use the aquarium water and squeeze out the debris from the sponge. 4. Discard the water and get more water from the aquarium. 5. Repeat Steps 3 and 4 until sponge filter is mostly free of debris.