Review on Penn-Plax Small World Aquarium Filter & Filter Kit with Replacement Cartridges - Effective Bio Sponge, Carbon, and Zeolite Crystals - Ideal for Freshwater and Saltwater Setups by Leticia Wilhelmsen

Filter is ok. Works well and everything, only with minor changes. If possible, you can take the top and bottom apart and replace the sponge you plan to use. And instead of carbon, use ceramic rings. They last longer (about 6 months). Buy a large box for about $3. The filter fits 6 ceramic rings. This will last around 6 months or longer depending on how small or large your tank is. It also doesn't come with a check valve and extra hoses. A check valve is needed to prevent water from leaking out of your tank in the event of a power failure and possibly breaking your air pump. Now for the noises, I hear this low whistling. I'm the type who can tolerate filter noise, but that whistling sound is pretty loud. I would not recommend this filter for those who are easily annoyed by the noise of the motor as it creates a whistling noise. I would recommend other sponge filters. They're not that expensive, just pay a few dollars more or less for them. This filter is not worth your time if you need a good and working tank. Edit: The filter material is much cheaper. It's already worn out, the bubbles are slowly coming out. I've added more photos here. I swapped the sponge for a better one. The flow is now steady. I use this filter as a secondary filter for my aquarium. I don't mind if it doesn't have suction as I don't use it as the main filter and no one should buy this filter if that's all you will be using. 1 star off because of cheap material. For now, don't even try to buy this filter unless you mind making some modifications like I did.