Sponge Filter Details


Our sponge is made from the finest reticulated waterproof filter foam in the world. It is extremely durable and completely fish safe.  All filter parts are made here in the USA.

  • 3.25" cube filter has a volume of 34 cubic inches  
  • 4.25" cube filter has a volume of 77 cubic inches
  • 5" cube filter has a volume of 125 cubic inches

PPI - stands for Pores Per Inch. 50ppi has 50 pores per inch (small pores). 15ppi has 15 pores per inch (large pores).

  • 15ppi (blue color)
  • 30ppi (black color)
  • 50ppi (Charcoal color)

There are different styles that mostly differ in how they sit in your tank. 

  • The Slate-bottom filters are heavy and stay solidly on the bottom. They are easy to slide out of the way when catching fish. Unlike some tiles, slate is completely safe and natural for the fish. 
  • The MAG filters use powerful epoxy-coated magnets to attach to the aquarium. One on the filter and one that you place on the outside of the tank.  Some prefer these because you can put these anywhere you want and have them stay in place.  Place a dab of silicone or tape on the outside-magnet to keep it in place when you remove the filter. These filter are also super easy to clean. 
  • The Internal-Weight Cube Sponge filters use glass balls to weight them down. They are not as heavy as the slate-bottom filters, but much easier to clean and the glass balls will never fall out. Some like to use these suspended in mid tank.  They work very well like this.

Assembly: Insert airline into the small hole drilled in the side of the top of the lift tube. Then push it to with 1/2" of the bottom. Then, insert bottom of lift into the small hole in the Sponge. Push the lift tube in about 1". It should be a tight fit.

If the filter floats to the surface shortly after putting it into your tank, that means that air is trapped in the foam. Squeeze it thoroughly while holding it under water to remove the air. It helps to remove the lift tube while doing this. The foam is more dense than water and always sinks if there is no air trapped.

We were the first company to offer the weighted cube filter back in 1987. We were first to use reticulated foam for our sponge filters (now the industry standard) and we have now developed the Mag Filter and the Internal-Weight Filter,  which are further steps forward in sponge filter technology. We offered the best in 1987 and we're still making the finest reticulated foam filters today. We use the highest grade reticulated foam available anywhere. There is none better.