Review on HITOP Submersible Aquarium Internal Filter: Adjustable Underwater Filter & Water Pump for Fish Tank up to 15 Gallon by Joshua Mejia

This product is very good! It's small and efficient. It fits almost every tank. I bought two of these and placed one at each end of my 20 gallon Walstad tank (hence the dark water due to the tannins in the soil). Creates a smooth and even flow of water. Depending on the flow pressure angle (long in my case) it can be noisy. The deeper it is directed into the water, the quieter. Assembly is easy, but if it's not sufficiently submerged in water, it won't work. One of mine makes a weird noise if it's not submerged deep enough and the other acts like it's not plugged in. But once they're submerged enough, they both work great. They are easy to clean and disassemble. I would recommend this product as it is affordable and does the job!