Review on Aquapapa 4X Dual Bio Sponge Filter for Betta Fry Aquarium Fish Tank - Up to 30 Gallon Capacity - Ships from California, USA by Elizabeth Sautner

Excellent price! I prefer this smaller size, it's perfect for any use or tank size and easy to hide! I use them like regular sponge filters attached to an air pump. I also use them as a pre-filter for my canister and HOB filters. I've even attached a few to the air intake of my polishing powerheads. Yes, sponges are good, but this is desirable as they keep the water clean. Only a small amount of water needs to be squeezed into the aquarium weekly, so it's very easy. I bought large sponges and cut them to replace the thin sponges on my canister filters as the flow is much higher. I have large numbers of fish in all my tanks, I am the worst overfeeder in the world but over filter and they still manage to keep the water spotless with minimal maintenance.