Aquatics Unlimited: Articles: Check Valves
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Check Valves

for the week of 7/2/98

Sometimes it pays to be prepared for a somewhat unlikely scenario. For example: on occasion, an air pump will suddenly lose power or an old, stiff airline will disconnect from it. This doesn't seem like much of a disaster at first, but if the circumstances are right, water can shoot upwards in the airline tubing and gain enough momentum to actually begin a siphon inside the airline tubing. Water drains backwards through the air system, ruining the air pump, possibly draining the aquarium, and creating a puddle and shock hazard on the floor around the aquarium.

Fortunately, for a couple of bucks, a check valve can be installed, which allows flow in only one direction. Air flows easily toward the aquarium, but should the pump be interrupted, neither air nor water can rapidly flow away from the tank. Many air pump manufacturers highly recommend check valves - especially those who also manufacture them.

There are several varieties of check valves, and the types with the little flattened rubber nipple inside seem to be a bit more reliable than the old spring-loaded type. Installation is simple: just cut the airline about a foot or so from the pump, and insert the valve. If aeration does not resume in the aquarium, the valve was installed backwards.

Eventually, the moving parts in the check valve begin to stiffen, corrode or wear, so they should be tested at least annually. Simply remove the valve from the system and trying inhaling and exhaling through it; air should pass easily in one direction, and with great difficulty, if at all, in the other.

Submitted by: Jim Kostich

"Tip of the week" appeared regularly in 1999 and 2000.

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