How to Prime a Pool Pump

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What Does It Mean to Prime a Pool Pump?

Pool pumps break down quickly in the absence of water. They work much like car radiators; the waters that flow through pool pumps are integral to those pool pumps’ abilities to cool themselves. If you power your pool pump without adding the necessary water, it will likely be broken within a matter of minutes. 

That’s what it means to prime a pool pump. You add the water before turning that machine to “on.”

Does Your Pool Pump Self-prime?

Technology is great, isn’t it? It’s possible that your modern marvel doesn’t actually need your help because many pool pumps are self-priming. If you don’t know if your pool pump can self-prime or not, read your pool pump’s accompanying manual to see if you need to manually prime the pump. 

If you’ve lost the manual, it is almost certainly on the internet. To make it easier, we’ve listed links to the manuals of a few of the most popular brands. A couple of these companies also list diagrams, instructional videos, and troubleshooting guides which might come in handy.




How to Prime a Pool Pump

Step 1: Make Sure the Pool Pump Is Off and Pool Plugs Are Removed

The pump should be set to “off.” This is obvious to most experienced pool owners, but we don’t want to chance any emails saying that you fried your pool pumps. 

Additionally, if you are still using pool plugs from winterizing your pool, remove them. We need water to flow freely if we are going to prime the pool pump.

Step 2: Set Diverter Valve to Recirculate

The diverter valve is sometimes referred to as a multiport valve. In this case, the purpose of this multiport valve is to connect your pool to one of two water sources: the main drain or skimmer. Typically, the valve will be set between these two options, so that both sources can be let through to the pool. When we prime a pool pump, we only want one of those sources to be let through.

The options here can read a bit differently depending upon the system. If you see the option, “recirculate,” turn the valve till that is chosen. If you don’t see “recirculate,” turn the valve until only one water source is being let through to the pool pump.

Step 3: Relieve Air Pressure

Note – Throughout this article, we will refer to an air pressure relief valve. However, some filter systems operate without a relief valve. They are designed to relieve pressure automatically. In those cases, simply ignore any instructions specific to relief valves.

Water cannot occupy space that is already occupied by air. In order to let the water into the pool pump, we need to let the air out of it. Air is lighter than water, so the air relief valve is naturally placed at the top of the pool filter. Do not close the air relief valve until the end of step 8.

Step 4: Clean Out Pump Basket

Your pool pump will have a lid on it. When you remove that lid, you should see a basket. We highly recommend that you take out the basket and rinse it off.

This is semi-optional. It is also very easy to do, so don’t skip it. The filtration basket in the pool pump picks up random bits of debris, and those stacking pieces of debris hinder water flow and increase water pressure. Increased water pressure breaks down equipment faster and increases the cost of running your filtration system.

Step 5: Check for Damage and Potential Air Leaks

Successfully priming your pump will largely depend upon the ability to secure the pressure within the pipeline. If there is a crack in the lid of the pool pump or a gasket/o-ring is poorly sealed, those circumstances can potentially prevent your pool pump from priming.

If the gasket (o-ring) feels too clean, you should add some lubricant (Not petroleum jelly) to it. It will increase its ability to seal against potential air leaks. Some lubricants are listed as being formulated for pool use, but any silicone lubricant should work just fine. 

Have you determined that your pool pump system has developed a leak and can’t find it? If so, we recommend that you click over to the article “How to Identify and Fix Air Leaks.” Much like this article, we have written a step-by-step guide to help you to find that air leak.

Step 6: Add Water to the Pool Pump

Stick the hose into the pool pump and turn it on full blast. Let the water rise to the top and quickly put the lid back onto the housing. You’ll need to be quick, and you should tighten the lid by hand.

Step 7: Turn on the Pool Pump

Turn on the pool pump. If everything is working correctly, water should be flowing smoothly within the next 45 seconds. 

If not, turn the system off and go through the steps again. Give extra attention to finding sources of leaks. Is the lid on tight? Is the o-ring making a secure seal? 

Side note – The air relief valve should still remain open during this step. As the water flows and fills, that raising water forces out the trapped air within the system.

Step 8: Wait Till the Air Is Expelled, Then Close the Air Relief Valve

When the water is running smoothly, the trapped air will likely make an audible hiss as it is forced out of the air relief valve. When the air has been successfully forced out by the raising water, you should close the air relief valve.

If you need a visual confirmation, look into the pump basket. The air that is being forced out of the relief valve can be seen through the glass viewing port. Bubbles will keep passing by until they have been forced out of the system. When most of the bubbles are gone, the pump is running as it should.

Step 9: Turn the Multiport Valve / Diverter Valve to its original position

If the water is flowing, it is time to return the diverter valve to its original position. Turn it slowly. 

This can potentially release some air from the reopened pipeline. Just in case, briefly reopen the air release valve and close it again.

If it all went smoothly, your pool pump should be primed. If it didn’t go smoothly, please continue reading. We have listed some common questions and answers that might help.

Questions, Answers, and Troubleshooting

It takes my pool pump several minutes to prime. Is that normal?  

Generally, it should only take a couple of minutes or less to fully prime. Anything more is often a sign of an air leak. It’s dangerous for the equipment to attempt to prime for extended periods of time. If water isn’t successfully flowing through the equipment, the equipment will burn out and break down very quickly.

The pool pump won’t fill up with water. Why?

There can be several reasons, but the common reason is that the check valve is broken. Without it, the water will flow into the pool as you try to fill the pool pump.

There is one super-easy way, without directly looking, to tell if the check valve is broken. However, it only works on pools with hot tubs. When your pool pump is off, does the added water flow into the hot tub? If yes, the check valve is broken because it didn’t keep the water in the pipeline.

If the check valve isn’t broken, check the seals again, and try adding some water directly into the skimmer. While you’re at it, check to make sure your pool’s water level is high enough to meet the middle of the pool skimmer’s entrance. Adding water can help to get the process moving when there is too much air within the system. 

I can’t find a diverter valve anywhere?

We don’t know of any pool pumps that don’t have one, so it should be there. The look can vary slightly, but the basic shape should look the same. Maybe this picture will help? 

Is the pool drain blocked?

Like a clogged bathroom sink, a clogged pool drain will stop the water from flowing. Unfortunately, you need to swim in these waters, so a toxic Drano Max just isn’t going to cut it. What you need is a drain-clearing bladder that can force the drain clear of debris.

In Conclusion

Let us know if you have any questions. If we think it will be useful, we will add the question to the list above. Thank you for reading. We hope it was helpful to you.

The Pool Care Handbook & Video Course

by Swim University
This is an illustrated e-book with detailed videos and step-by-step instructions on how to best care for your swimming pool. 
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