Most are powered by an airstone. The airstone causes water to lift up in the tube and thereby causes a slight suction around the sponge that pulls debris towards it.
You can also find powerhead powered sponge filters...they have better mechanical filtration and I bet your plecos would be safe.
Another alternative is to use a sponge pre-filter for whatever filter you're using now.
You can also find powerhead powered sponge filters...they have better mechanical filtration and I bet your plecos would be safe.
Another alternative is to use a sponge pre-filter for whatever filter you're using now.