Swimming Pool Blog

Clogged Pool Pump Impellers

by Sean Griffin, February 28, 2010

Clogged Pool Pump Impellers 

bronze pump impellerConnected to the shaft of your motor the impeller gives your pool pump the ability to move water. When the impeller is turning at the proper RPM, it is creating a vortex - sucking in water and spinning it off through channels directing the water out of the return side of your pool pump. When operating properly these components along with the motor are the driving forces behind your pool filtration system.
At the point of the impeller is when the vacuum or suction from the pool converts to pressure going back to the pool. Without a properly functioning impeller your motor will spin without purpose. To achieve proper flow, an unclogged unobstructed impeller is vital.
Although the design of pumps has changed over the years, pump impellers are basically the same and have the same possibilities to become clogged. When designing a filtration or circulation system proper strainers are set in place to prevent debris from entering the impeller. For pools and spas this means a skimmer basket, main drain grate and a pump basket. In theory nothing should be able to clog up the works but this is just in “theory” and as we all know is usually not the case. Whether a skimmer pump basket becomes broken or the debris is smaller than the holes in you baskets, junk always seems to end up making it to the impeller. Grass Clippings, Pebbles, Spring tree debris, pet hair, etc.
Take the necessary steps to ensure or limit anything making it to the pump and beyond. The key is preventing before recognizing clogged impeller and having to correct.

Older pumps use a brass or bronze impeller. These older style impellers were known for their heavy duty nature. Although they were subject to corrosion due to water chemistry, they are very difficult to clog due to their open face design. I compare them to a wood chipper. Anything that made it through your skimmer basket and pump strainer would surely be broken down and end up in the filter. As the industry leaned toward constructing pool equipment using heavy duty ABS plastics these older units became less common. 

Proper preventative measures are in place to prevent clogging but you should be aware of the signs and symptoms and how to correct if need be. Additional to avoid clogging remember to inspect all baskets and filtering devices before pump, and make sure when changing out a dirty pump basket to remove any debris that might fall behind pump strainer (usually can be scooped out with your hand), and if you find you are subject to small debris or hair use filter savers

I have known homeowners to use leggings or panty hose during the spring, in either the skimmer basket or the pump basket. For manual pool vacuuming, it helps to utilize a vacuum plate on the skimmer basket or an in-line vacuum leaf trap so you don’t clog plumbing and overload your pump basket which can eventually result in impeller clogging.  

Signs that your pool pump impeller may be clogged:
  • Lower than normal filter pressure.
  • Noisy pump, straining noise or caviatation noise.
  • Slow, swirling, air filled motion inside pump basket, viewed thru clear lid.
  • Reduced action at the skimmers and returns.
How to clean a clogged pump impeller:
Pumps vary in design so the troubleshooting procedure differs. Some pumps are big enough for you to remove the basket and reach your hand through housing to try and pull out any obstructions from the center of the impeller (make sure pump is off first, lol). Sometimes it doesn’t even require disassembling pump. If the impeller is really clogged you will need to "crack the case" or open up the pump. Usually this is accomplished by removing a clamp band or 4-6 bolts connecting the seal plate to the volute.
Using a thin wire or applicable hand tool you will be able to remove debris out of the individual channels or vanes of the impeller, without having to remove the impeller from the shaft. Like anything else an impeller can break. When you unclog a suspected impeller always inspect integrity making sure there is no warping and the impeller spins freely and is properly attached to the shaft of the motor whether it is threaded or keyed on. Small cracks can be filled with super glue; and small chips on the impeller vanes don't affect performance.
Whenever disassembling your pool pump, mind the mechanical shaft seal located behind your impeller. The seal is what creates a water tight seal along the pump shaft. If you remove or replace your impeller it is recommended to replace the shaft seal.
small impellerUnclogging your pool pump impeller is a chore so when you end up back there at the pool equipment pulling dog hair out of the pump, save yourself the headache and put your energy into prevention. Some pumps are known to be more clog prone than others, but if you have a repeated problem, find a way to trap the debris upstream from the impeller.