Review on Penn-Plax Undergravel Aquarium Filter for 10 Gallon Tanks - Enhance Water Clarity & Purity - Freshwater/Saltwater Safe - Two 9.5” x 9.5” Plates by Leslie Aragon

I bought this product to upgrade to a larger aquarium for my angelfish farm and a few other fish. Easy setting. Rinse everything with hot water. I rinsed the carbon filters with hot water for five minutes. The same goes for new gravel. I installed the tank with 20 gallons of water from the old tank. Make sure the temperature is the same as the other tank, install all accessories, install carbon filters in the airflow as indicated. Everything seemed fine, after 6 hours I noticed foam coming off the hoods, and $100 Healthy Fish was gone! I'm pretty sure the problem was with the carbon filters. If someone else is using this filter system, DO NOT use activated carbon filters! I am very saddened by the loss, especially of an adult breeding angel pair. I will never buy a Penneplex again! I have owned and raised fish for over 20 years and this has NEVER happened.