Filters & Overflows » Overflow Boxes

What is an Overflow Box?

Also known as siphon boxes or prefilters, an aquarium overflow box helps keep your air pump and filters working by making sure they won’t be damaged by any power outages. If you have an aquarium of less than 40 gallons or if your tank has been thriving for years AND you have working spare filters and air pumps, then you don’t have to worry about adding on an aquarium overflow box.

Aquarium overflow boxes are used mostly by professional aquariums and hard-core aquarium hobbyists as insurance for their expensive and vital equipment. If the power goes out, then water can back up to short circuit the air pump or the filtration unit. Some folks make their own aquarium overflow boxes but there are also ready made ones.

Power outages can also lead to your tank suddenly overflowing. If your tank is not on the ground floor level of your home and it is more than ten gallons, then you should really consider some kind of aquarium overflow box. A filled tank with gravel or sand and ornaments weights hundreds of pounds.

Most salt water tanks will have some gentle of sump pump that are far stronger than for a freshwater tank. When it’s on, the water is kept level because it’s moving around all of the time. But when the power goes out, the water has nowhere to go except into the tank and onto your floor unless you have an aquarium overflow box.