Overflow box creates an overflow to a standard aquarium without any structural changes. Overflow is used for flowing water to a separate filtration aquarium (sump) located under the main aquarium or when several aquariums are connected to same filtration system. Overflow is very useful especially in larger marine aquariums as technical devices used for water quality maintenance can be removed from the display aquarium, there are more options for water filtering arrangements in a sump, water volume in the aquarium system is higher and overflow prevents a surface film creation on the aquarium water surface.

Overflow box does not siphon water, so the water level in the main aquarium does not change. Waterflow through the overflow stops when the return pump is stopped and water is not added to the aquarium anymore. Overflow continues automatically when the aquarium water level begins to rise after the pump is turned on.

This overflow box is made from transparent acrylic. Measures 15,3*18,8*30(20)cm. It can be fitted to an aquarium with max. 40mm wall thickness and the overflow intake extends up to 75mm below the aquarium top. The intake has a comb-style grill, which is adjustable according to the water level in the aquarium (in order to make the intake opening completely watertight below the determined water level, a thin silicone seal should be glued around the grill plate). There is a valve in the top compartment for easy air removal.

The outlet diameter is 40mm, so it is suitable for 40mm PVC pipe or hose. The connector part is removable and can be changed to a smaller diameter part. Flow capacity with 40mm outlet is max. 4000 l/h.

NOTE! Overflow system, whether an overflow box or a built-in overflow, causes a risk of aquarium overflowing to the floor and water damage to the property if the overflow intake gets blocked. Therefore, it is recommended to position the return pump in a way that all the water that the pump can pump up to the aquarium will fit there in the case that the overflow is blocked. This can be carried out by positioning the return pump in a small watertight section in a sump, which gets water from its own overflow. Hence, if the aquarium overflow is blocked, the return pump overflow stops also and only the water in the pump compartment will be pumped up to the aquarium. Running dry can damage the pump, but a broken return pump is easy to replace and much better option than water damage to the floor.