I used under gravel filters for years with no issues other than fish that dig. I got out of the hobby for several years. When I came back aquariums on the internet had exploded. Many things had changed. One of these changes was how everyone hates under gravel filters. In my opinion, this is primarily due to marketing.
Marketing is the same thing that drives the hang on back filter systems that use cartridges. The primary reason behind these is the need for companies to get repeat sales. If you are using under gravel filters and don't break them, they get one sale.
I have sponges, hang on back filters, and canisters currently in use. I even have a few box filters. I have experimented with every sort of filter I can find and have made or modified a few of them. The only ones I really like are the sponges.
I think for me the air driven filters are the best. I live in hurricane country. During a hurricane, I can lose power for a week or two at a time. With a box of D cell batteries and a few battery powered air pumps, I can keep my filters running. Currently, I have sponge filters in all my aquariums in addition to the other filters that I have. This more sponges than I need to run the aquarium so I can keep my biological filters going when the power goes off.
I think that in the future I will be switching all of my aquariums that have substrate to under gravel filters. I will keep sponges for bare tanks and new aquariums.
Watch this video. Cory makes a lot of excellent points.
