Which is better an undergravel filter or a corner filter?
Both do the job they need to do, but undergravel filters are by far the worst kind because they are very difficult to clean, and encourage waste to get trapped under the filter plates to build up and degrade water quality over time, while any other filter can simply by removed and rinsed off in tank water from a water change. But by corner filter it can come in 3 different varieties – internal power, air driven sponge, and air driven box. Internal power filters have the advantage of being quiet, but the disadvantages of not aerating well, and not holding much media, making them only good for very understocked tanks. Sponge filters have the advantages of being very, very efficient and effective for all stocking levels. This is my own choice of filter for my small tanks and they are just wonderful – superior to power hanging filters, and the only disadvantage is the space they take up, but it’s worth it. Box filters have the advantage of being able to customize the media, but are general
