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Back to Basics: The Importance of a Properly Functioning Skimmer

Posted by E-Z Test Pool Supplies on May 15 2017

Back to Basics: The Importance of a Properly Functioning Skimmer

OK, so you’ve just read the title of this week’s blog and you’re probably thinking, “What could possibly be such interesting and valuable information about my pool’s skimmer that it warrants a whole article about it? I mean it’s only a hole in the side of the pool where the water leaves and goes to the pump and filter – that’s it, right?” As it turns out, there’s a lot more to swimming pool skimmers than you might think.

swimming pool skimmer

Pool Skimmer w/ Weir Door

  • So what should I be looking for that’s so important when it comes to the pool’s skimmer(s)?
  • What is the purpose of the weir door?
  • Do I need a weir door?
  • How important is my skimmer basket?
  • Do I even know what a skimmer is?? Just kidding on the last one…I hope.

Your pool skimmer is more important than you might think. Keeping the skimmer clean and functioning properly has far reaching effects on the pool that you may not expect. So what is a skimmer and what does it do? Well, first off it is a large rectangular opening

with a weir door that controls how water enters the skimmer, a basket for catching some of the larger surface debris and a hole at the bottom of it which connects to filter hoses on an above-ground and pipe on and in-ground. It is where water leaves the pool before arriving at the pump and filter, the first line of defense at removing debris from the pool, and also the spot where your vacuum hose is hooked up when it’s time to clean your pool. For most of you reading this blog this is information you already know. Now let’s address some things you may not know.

OK, if you were
wondering, the weir door (or flapper if you like) really does have a purpose other than making your life difficult when it comes time to vacuum. The weir (aka flapper) has a few functions: 1) it allows for debris floating on the surface to be removed from the pool more easily than without it, 2) it keeps that debris in the skimmer basket area when the pump shuts off, and 3) it prevents gulps of air from entering the pump and filter system while people are in the pool.

pool skimmer diagram

How your Skimmer Works

Here’s how a weir door functions: Because water is entering the skimmer while the pump is running and flows inward, the top of the weir door pulls in a bit and forces more water to enter the skimmer more from the surface rather than from below the surface. This creates the effect that you see of water flowing over a dam. Greater flow from the surface of the water translates to greater removal of surface, floating debris that would not be taken out as effectively without the weir. Here’s another way to picture this – take a garden hose with the water on and place it 6 inches or so under the surface of the water so that the water is flowing parallel to the surface of the water. Now raise the hose so that the flow is still parallel to the top of the water but very close to the top. You’ll notice there is a much greater effect on making the surface water move more quickly and in larger quantity. This is the effect desired in a pool and where you actually produce skimming action. It is the skimming action that removes floating debris (leaves, insects, pine needles, pollen, etc.) to a much higher level than without a weir.

Also, picture this – you’ve been running your pool all day and have caught a good amount of debris in the skimmer basket, and now the pump shuts off for the night – something most pools do. With no flow from the pump and a missing weir door, the tendency is for all of that junk to float right back out into your pool. Not what you want.

Last, the weir door plays a big role in regulating the flow of water into the pump and preventing large amounts of air from entering your pool’s pump and filtration system. This is something that can be much more serious than you might think. Air in the pump and filter generally increase the stress on your pump making it work harder and run hotter – not to mention noisier. In fact if things are running the way they should, with minimal air in the system, your pump should not lose its prime, it should be running with more of a purring sound than a growl, and you will likely add years to your pump’s life. Short story – use your weir door!

So what about the water level in the skimmer, does that matter? I mean as long as there’s water going in, that’s fine right? Not quite true. You should aim for a water level about 1/2 to 2/3 up the opening of the skimmer. Too low and you start to get gurgling sounds which are telling you that your pump is working way too hard at trying to keep the water flowing. Too high of a water level will still let water flow but cuts down on the efficiency of the skimming action that the weir helps to provide. In fact, allow your water to exceed the top of the skimmer opening and you will prevent most of the surface debris from ever entering the skimmer, since water will be drawn in from below the surface. At this point the pool will still circulate and filter, but the skimming effect will be lost.

On to the skimmer basket! OK, so how often do you check and empty your skimmer basket? It takes seconds to do but many of us miss this important detail. The skimmer basket is the first line of defense for removing undesired material from your pool, and if you let it build up you are greatly adding to the pump’s labor and shortening its life. In fact the same principle applies to cleaning the pump basket as well. A basket full of debris greatly reduces water flow, adds strain to the pump, and hinders adequate filtration. As the old saying goes, “garbage in…garbage out.” Clean those skimmer baskets regularly!

Last but not least, here’s an important part to your study today in the science of skimmer-ology. When you vacuum your pool, do you use a skim vac or plate that sits on top of the basket to hook up the vacuum hose? Or do you simply take out the basket and shove the cuff on the hose down into the opening below the basket, thinking you’re getting better suction than using a skimmer vac plate? It’s OK to admit it – I won’t tell anyone, but you may be creating much more of a problem for yourself. In addition to the fact that you may be creating too much suction for the vacuum to function properly – the kind of suction that glues your vacuum to the floor of the pool and makes vacuum handles snap off the end of the pole when you try to move it – that’s only part of the problem. I recently had a customer come in to the store who has an in-ground pool with multiple skimmers, that all seemed to be flowing well except for one that barely drew water at all. It took me a few minutes to figure out what had happened, but in the course of asking him questions I found out that he was sticking the vacuum hose directly into the skimmer below the basket and bypassing the use of a vac plate and basket. In the course of the conversation I also found out that he had recently vacuumed up a large amount of leaves from the bottom of the pool. Putting two and two together, I realized that by vacuuming this way he had thoroughly clogged his skimmer line with leaves and then needed the line to be professionally cleared to allow the skimmer to become functional again. All of this could have been avoided by using the basket and a skim vac plate.

We wouldn’t dream of taking our cars to a mechanic who threw out your car’s air and fuel filter because things seemed to “flow better with them out”, but we sometimes will make shortcuts with our own pool and equipment in the name of efficiency.

OK I’ll stop preaching. Keep swimming!