How to Select an Aquarium Overflow Kit

Overflow systems are a vital part of any aquarium and it is important to understand the different overflow styles in order to select the best one for your tank. If you are thinking about a new aquarium or already have a tank and want to improve its filtration then an overflow kit is a great choice.

Overflows work by using gravity to maintain a constant water level in the aquarium. They are self-regulating and really just a dam with overflow teeth that prevent water from flowing over the top of the overflow into your aquarium, but allow water to flow up through the overflow when the level in the tank rises above the height of the dam. This water then enters the overflow and flows down the drain into your sump. The top of the overflow also has a screen that helps to keep larger debris and snails from making their way into your filter system.

The best overflow kit will include a high quality pump and a hose with a large diameter. This will help to ensure that the pump can handle a high volume of water. The hose should be long enough to reach the bottom of the sump, but also allows you to easily control the water flow rate out of the aquarium. This can be done by adjusting the float valve at the top of the hose.

There are many different overflow styles available, some of the most popular being Herbie, Durso, and Bean Animal. Herbie and Durso overflows can be used with a single drain in the aquarium and do not require a bulkhead so they are more affordable than an internal hang-on overflow. However, Herbie requires two holes in the tank and will not be as quiet as a Bean Animal, but it still can handle a lot of water flow without gurgling.

An internal overflow box is a more expensive option but does take up less space in the tank and will be much quieter than the Herbie or Durso overflows. However, they will not be as flexible as a Bean Animal and will not have the emergency backup drain of a Herbie.

Another type of overflow is the external overflow kit which can be made at home for a relatively low price. These are usually made from PVC pipe and plumbing parts and are a good alternative to buying an expensive tank from a major marine aquarium producer. They are also a good solution for tanks where a sump is not wanted or needed.

If you have a tank with a built-in overflow, it is probably a good idea to install a sump. The evaporation that would normally happen in the aquarium will be relocated to the sump and this will result in a much more consistent water level. Having the ability to change the flow rate and cycle rate of the water in your sump is also a big benefit. Generally speaking, most hobbyists aim to cycle the water in their tanks about 4 times per hour.