What The Heck Is An Aquarium 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 a goldfish aquarium of fewer 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. 

Mainly For Salt Water Wet Pets

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 people 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 isn't 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.

How To Tell If You Really Need One

Most salt water tanks will have some softhearted 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.

Get a lot of old towels and newspapers around the floor of your tank, because things might get wet.  Get a bucket and a coffee can to bail if need be.  If you can, arrange for a friend to turn the power on and off while you are there at the tank.  Turn off the power.  If the water level suddenly rises more than one inch -- or if you have a suddenly saturated floor -- then you know you need an aquarium overflow box.

Going Shopping

Aquarium overflow boxes are available at many pet stores and aquarium area of expertise stores and their online equivalents.  There are ones specially made for large freshwater aquariums, so be sure you have one for fresh or salt water for whatever tank you have.  They vary in prices (like everything else) from under $50 (US) to $200 (US).  Most work with a solemnity flow system so you don’t need to break out a drill.