The swimming pool skimmer pulls water from the top of your salt water pool and removes leaves, bugs and other debris before the water gets run through the filter, rechlorinated and returned back to the pool. But the pool skimmer opening also provides another important purpose: It’s where you attach the end of your pool hose to vacuum your pool.

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Normally the pool skimmer has a very strong suction due to the small opening and close proximity to the pump. That and the fact that the only other way the pool pump draws in water is from the main drain at the bottom of the pool. When you lose skimmer suction, it may be because of a full skimmer basket, blockage in the piping, a leak, or most likely a water filter that either needs to be backwashed, rinsed or replaced. It may also be a problem with the skimmer valve that is either partially closed accidentally or on purpose and forgotten about.

Here are a list of things to check throughout your salt water pool system that could be causing you the trouble.

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Skimmer And Main Drain Valves

When we first bought our house with an existing pool, I had to familiarize myself with the pool system on my own as no training was offered and I didn’t feel like paying our pool company $75 for their pool school. Yeah, I’m cheap but I also like figuring stuff out myself.

We have standard white pool piping with the familiar red plastic handles to control waterflow. I learned that one valve opens and close the skimmer. One valve opens and closes the main drain. And a third valve always stays open and isn’t ever touched just because. That’s all I know and I don’t touch it.

The problem with these red plastic knobs is that with frequent use and with our harsh winters, eventually through opening and closing the skimmer over time for whatever reason, the plastic valve knob on the pipe starts to wear off and loses its grip. Just like a screw head gets worn out if you tighten and loosen the same screw repeatedly.

Long story short: A few times, I couldn’t open the valve completely because the threading on the red handle or on the valve actuator itself wore out and I left the valve closed.

Always double check to ensure that your valves are left completely opened when you want them open and that you didn’t accidentally shut them or restrict them. And if you have kids who like to play back there, they might have accidentally closed a valve without anyone knowing.

Pool Filtration System

In my experience, the biggest reason you lose suction anywhere in the pool system and why return water jets into the pool suddenly get really low flow is due to an issue with your pool filter. In all likelihood the filter needs to be backwashed (sand or D.E. filter) or properly rinsed (cartridge filter).

Our cartridge filter gets clogged when algae sets in and also late in the season if I haven’t rinsed it recently. I’m amazed by how much heavier the big cartridge gets (we have a 2-cartridge Sta-Rite System 3 filter) when it’s full of crud. The amount of sand and mud that washes out is unreal. It’s still heavy after rinsing but not quite as much as before cleaning it. Especially if algae is a problem. That really clogs filters. I’ve also had an inch of sand sitting at the bottom of the filter housing that I literally scoop out.

And occasionally after a few years of use, assuming the cartridges aren’t ready to be replaced they might need to be soaked overnight in a filter cleaner to reduce oils and other contaminants that a hose rinsing alone won’t accomplish. I was amazed at how filling a large, clean garbage bucket full of water and adding a $7 bottle of filter cleaner would help the cartridges when I popped them in and left them overnight to soak. I rinsed them off the next day, reinstalled them in the system, fired up the pump and felt the incredible strong force of water from the return water jets inside the pool.

Keep an eye on the pressure gauge on your filter because normally a PSI reading of 8 – 10 or worse means it’s time to backwash or rinse. Poor filtration can seriously affect water flow and suction.

Pool Skimmer Basket

Pool skimmers can get packed with leaves and debris over time and after heavy wind or a rain storm.

The pool skimmer basket gets filled with leaves and other debris. And occasionally a dead animal. Sad but true. All of this debris can block water flow especially if you haven’t checked the skimmer in a few days, were away from your house, have leaves and twigs that blow into your pool, or have had heavy rain and wind which blows more debris into your pool.

Our skimmer basket has also sucked in roof tiles that broke off during a wind storm as well as plastic chip bags and other junk that somehow flew into our backyard! This stuff definitely blocks and restricts water flow.

If something gets lodged in the skimmer, it can force the skimmer trap door open and if it stays open, water won’t flow in and it will suck air. I’ve that happen too. You will hear a problem if the pump is running though. You will hear the sound of air being sucked in and the pump struggling. The sooner you get to the problem, the better.

Pump Basket

Learn to listen for the sounds your pump makes. I notice right away from sound alone when the pump is sucking air and is having trouble pumping as just mentioned above. It makes a certain sound that means something is blocking it somewhere and I need to go look and find out quickly what’s causing it. In my experience, it’s often the pump basket that is full of debris especially if we had a storm or I haven’t checked the basket in a few days.

Do you empty the basket after every time you vacuum the pool? The pump basket collects all the junk from vacuuming. I have emptied completely full baskets full of leaves, twigs and other stuff that I couldn’t believe made it in the basket after vacuuming. Long twigs several inches in length, dead worms, leaves, mud and other crud. It’s several pounds heavy at times from all the vacuumed stuff it’s holding.

Main Drain

Do you have a main drain blockage? The main drain is at the very bottom of the pool at the very deepest part. It’s like a drain in a bathtub except that it’s harder to reach. Unless you like diving into the pool and going all the way down with goggles to check your main drain (Personal note: I’ve never done this!) you can only visually inspect the main drain while standing outside the pool looking down at it when the water is still.

How does it look? Is there anything blocking it or restricting flow? While a blocked main drain shouldn’t necessarily restrict skimmer water flow, if there is a blockage or leak down there, it’s going to cause you trouble either way. Remember: Things get sucked into the main drain by the pump so once it sucks something in, even with the pump shut off it might remain stuck there until it is removed even if you can’t see it from outside the pool looking down.

Pool Skimmer Water Height

I always use the pool skimmer as my gauge to ensure the water level is correct and to visually see how much water was lost since the last time I checked! Water evaporation in the summer (it’s real and significant) and water lost to splashing (not as big a deal) is easily visible when you use a common measurement to quickly look.

So every day I walk outside to the pool and take a look at the skimmer and make a note of where the water level is and compare it mentally to where it was the day before, or the last time I checked. You can quickly see when water needs to be topped or quickly spot a possible problem like a pool leak.

The water level for my pool needs to be 1/2 to 3/4 of the way up the pool skimmer. If it’s much lower, the skimmer won’t draw in enough water and will suck air. Not good! Water has to be high enough to flow into the skimmer inlet with no air present. This can negatively affect suction on the skimmer. You may need to add water to the pool if too much has evaporated which it will during the summer, with sunny weather.

If the water level is too high – typically if we get torrential rain which we have experienced – the water level is suddenly higher than the skimmer opening and won’t properly skim. This won’t negatively affect suction on the skimmer but it will stop the skimmer from skimming! So if you ever notice leaves floating throughout your pool or near the skimmer, it might be because the water is too high. You may need to drain water until you have the proper height.

Vacuum Hose And Head Attachment

This isn’t a problem with the skimmer per se but if you’re having vacuum cleaning problems with little suction, I can almost guarantee you have something stuck in your hose. The pool hose tends to be very long so it can reach each part of the pool. That means there a lot of space inside the hose for things to get blocked. If you pick up a hose, it’s fairly heavy given it’s long length. So twigs, mud, leaves, etc may get caught insight without you knowing about it since it’s already a heavy object to begin with. And it causes problems with vacuuming.

Since the hose isn’t transparent, you can’t see the blockage even though it’s there. In my experience, twigs and then leaves from the bottom of the pool get clogged over time and cause the vacuum to work improperly. I’ve had to take the pool hose and either knock it against the ground to loosen blockages or hose it out with a high pressure hose to clean it out.

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The skimmer is used for not only skimming the top of water to remove leaves and other floating debris but also for pool vacuum cleaner. You can lose suction in the skimmer for a number of reasons as mentioned above but the main ones in my experience is a blockage somewhere in the piping, a packed skimmer or pump basket or more likely a filter that needs to be backwashed, rinsed or replaced. Specifically, the sand in the case of a sand filter or the cartridges in a cartridge filter may need to be replaced if after cleaning, the problem remains and you can’t locate a blockage, leak or other issue.