Vacuuming pool can clog up skimmer suction line

Q: I have a big problem with my swimming pool. I came home from work and noticed that lots of leaves and debris were floating on it. I lifted off the top of the skimmer and noticed that the water was not moving, and there was no suction. I have tested the pool equipment, and it seems to be working fine. If I move the suction valve to the “drain,” the pressure is good. However, if I move it to “skimmer” the pressure drops and the motor makes a loud noise. What can I do?

A: You can either run your motor on “drain” suction or risk burning out the motor — at least until you locate and remove the blockage in the skimmer line.

It’s uncommon that you encounter an obstruction like the one you described. My guess is that you may have neglected the pool and are just now noticing the problem.

There are safeguards against such a blockage, namely the basket strainer in the skimmer. It may be that your basket has lost the weight (usually the handle) that holds it down into the well. Without the weight, the basket floats, and debris will bypass the basket right into the pipe.

As the suction from the pump pulls water through the basket, debris floating on top gets pulled into the basket. If debris gets past the skimmer basket, it will then go to the motor basket. If it’s too small for that, it gets caught in the filter media.

One way you can clog up your skimmer suction line is when you vacuum your pool. Since you have to remove the skimmer basket to insert the vacuum hose, debris goes straight into the line.

If you have a lot of trees, you may be sucking up lots of leaves and pine needles. All it takes is a few elbows in the pipe to choke it up and stop the flow of water.

Incidentally, your motor makes a loud noise because it is straining to move water through the blockage (you might also notice the pressure gauge drop).

So how do you clear the line?

It will be hard to tell exactly where the blockage is located, but it should be somewhere between the skimmer and the valve. Start by turning off the motor and opening the motor’s basket pot.

Insert a 2-inch drain cleaning bladder bag attached to the end of a garden hose, and push the bladder into the pipe and turn the valve so that the skimmer side is completely open.

Turn the hose on and the bag will start to expand against the interior of the pipe before it will shoot short bursts of water into the pipe.

You can go look in the skimmer to see if any debris is flowing out. To further build up pressure, place a tennis ball over the opening of the pipe in the skimmer and hold it down against the opening for about 10 seconds. Quickly remove the ball, and, hopefully, you’ll see debris coming out.

If not, you can try snaking out the pipe. If you run a snake down the skimmer, you probably won’t be able to grab the obstruction, since it will probably be either a clump of leaves or a rock that you sucked up while vacuuming.

If nothing has worked yet, go back to the pool equipment and bring a screwdriver.

Go over to the intake valve and disassemble the top (the handle is attached to the top). This is the valve that directs the suction from either the drain or the skimmer.

The valve will have two pipes leading into it — one from the skimmer and one from the drain. Take it apart by removing the screws on the top and gently pull the top off of the valve.

When you remove the top of the valve you may see the clump of debris clotting up the skimmer side. Take the drain cleaning bladder bag and stick it deep into the skimmer (remove the skimmer basket and stick the bladder into the pipe just as you would when vacuuming).

Turn on the garden hose so that the bladder starts pulsing water down the pipe. The water will be flowing in the direction it normally flows when the motor is running.

Now if you are lucky, you can reach in and grab the debris out of the pipe, otherwise, the bladder will move the debris through the pipe and into the valve. This is commonplace for a blockage because there is a 90-degree elbow that leads to the valve.

Once you clear out the debris, reassemble the valve and turn the motor back on. Bleed out the air and your motor should run quietly and you should have good pressure and water flow through the skimmer. Add some pool shock and your pool should go from soup to sparkling in a few days.

Mike Klimek is a licensed contractor and owner of Las Vegas Handyman. Questions may be sent by email to handymanoflasvegas@msn.com. Or, mail to 4710 W. Dewey Drive, No. 100, Las Vegas, NV 89118. His web address is www.handymanoflasvegas.com.