Aeration Backup

Don’t Put All Your Eggs in One Basket

Modern power filters and canister filters are remarkable inventions: for a few pennies worth of electricity, they filter, circulate and even aerate our aquariums. Properly sized and maintained, they can handle all but the most crowded or overfed aquariums – so well, in fact, that some hobbyists choose them as their only source of current in the aquarium. While there are some obvious advantages (no spraying air pumps and fewer electrical devices installed and maintained) to this practice, there can be considerable risk as well.

As filters perform their primary function – the collecting of solid and dissolved waste – filter media clogs and flow rate begins to drop. A filter rated at 350 gallons per hour can slow down to 250, 150, 50, and eventually 0 gallons per hour. And while most aquariums could last for days or even weeks with poor or no filtration, the loss of aeration is another matter entirely. Whole tanks of fish can be lost in a matter of hours in extreme cases, or weakened and stunted where lack of oxygen is a more chronic problem.

This was much less of a problem for yesteryear’s aquarists. Filtration was frequently performed by a submerged box filter, powered by an air pump. Even if the filter media clogged completely, aeration was not affected.

One solution is simply to clean or change filter media religiously. The aquarist should either set up a schedule that never allows the filter to slow substantially or inspect the flow rate frequently, and clean/change when flow begins to decrease. This, unfortunately, is far more easily planned than carried out.

A better, more reliable option is to back up the filter system with an independent aerating system. An inexpensive air pump and airstone combination or a “power head” water pump fitted with a coarse foam sleeve can aerate effectively for extended periods with little attention from the aquarist. These should be installed to provide maximum agitation at the water’s surface, where gas exchange takes place.

Submitted by: Jim Kostich

“Tip of the week” appeared regularly in 1999 and 2000.