Review on 🐠 HuYaYa 4 Pack Pre-Filter Sponge Rolls for Fish Tank Aquarium - Compatible Foam Pre-Filter Accessories for Filter System by Amy Moore

I've used one for 3 weeks on an AquaClear 50 in a very crowded 10 gallon tank (40+ mollys produce a lot of poo). When the sponge is new or well washed, tap water flows through it with almost no resistance. I didn't notice any less water when I first installed this pre-filter, nor any noticeable drop after a week. But two weeks later, the performance really dropped. When I ran a faucet through a dirty sponge, it felt heavy because it was harder for water to flow through. So warning number 1 is that you should clean it regularly, otherwise your filter will not work as well and you risk burning your engine. Rub the material against itself as you clean to remove deeply embedded or ingrained residue. This improves flow and increases the time between brushes. If you push an inlet tube with a blunt end (like the end of a drinking straw) all the way in, all of the water should eventually flow through a tiny disk of spongy material. Concentrating the flow means faster clogging, less flow and less stress on the engine. The AquaClear tube is actually slightly smaller in diameter than the sponge's opening, so I use a rubber band to hold it in place. Even if your tube is wider, you can use a rubber band or zip tie to hold the sponge in place with minimal insertion. The insertion problem is compounded by a manufacturing defect on 2 of the 4 units I received. See photo. On the two devices I plan to use, the hole is about 7cm deep, which is almost the full length of the device as you would expect. However, on the other two devices, the hole is only about 4 cm / 1.7 inches, which is about half the length of the device. A shallower orifice means more flow restriction and faster clogging, even if you install it with a minimal effort. Therefore 4 starts instead of 5.