There are a thousand different ways to assemble a PVC drain for your aquarium, and everyone seems to have their opinion. Many claim theirs to be the quietest drain, but there is only one way to put them to the test. You have to build them, and some of the drains can get quite elaborate. Their only function though is to create a silent siphon that drains water from the aquarium to the equipment that sits underneath the tank. The simplest of drains is merely a hole in the bottom of an overflow box. These can get quite loud, so it’s best to use some sort of standpipe with a hole above the water line to allow air in. If this hole isn’t present, your drain will sound like a very loud toilet flush.