Your pool pump is the absolute heart of your pool system. Day in and day out, it works behind the scenes to keep your water moving, properly filtered, chemically balanced, and perfectly safe for your family to swim in. But when that pump suddenly loses its prime, everything comes to a grinding halt. Within just a few days of stagnant water, a pristine blue pool can start turning into a cloudy, algae-ridden mess, and that is exactly when stressful pool problems start piling up.
If you walk out to your equipment pad and hear your pump loudly humming or buzzing without moving any water, it is easy to panic and think you are facing a massive, expensive repair bill. Fortunately, a lost prime is one of the most common issues pool owners face, and it is usually something you can fix on your own without waiting around for a service appointment. In this comprehensive guide, we’ll break down the entire process into plain language and walk you through each step so you can safely purge the trapped air and get your pool pump running smoothly again fast.
What Does Priming a Pool Pump Mean?
A pool pump moves water by spinning an impeller inside it. But for that to work, the pump needs to be full of water first. If there’s air trapped inside, the pump can’t pull water from the pool and it runs dry.
When a pump loses its prime, it means air has got into the system. The pump runs, but no water moves. This can damage your equipment if you leave it too long.
Priming simply means removing that air and filling the pump with water so it can do its job again.
Why Do Pool Pumps Lose Their Prime?
Before we get into the how-to, it’s helpful to know why this happens:
- The pool water level dropped too low
- You recently opened your pool after winter
- There’s a small air leak in a pipe fitting or lid
- The pump basket lid wasn’t sealed tightly
- You drained water from the system for a repair
- There’s a clog in the skimmer or filter
Once you know the cause, you can fix it so it doesn’t keep happening.
What You'll Need
You don’t need fancy tools for this job. Here’s a simple list:
- Garden hose with running water
- Teflon tape (plumber’s tape)
- A flat-head or Phillips screwdriver
- Replacement O-ring (optional, but good to have)
- A towel or rag
Steps to Prime Your Pool Pump
Step 1: Turn Off the Pump
Always start by switching the pump off completely. Don’t just hit pause, go to the breaker or the power switch and shut it all the way down. You never want to work on a pump that’s still connected to power.
Step 2: Check the Pool Water Level
Look at your pool. Is the water level sitting at least halfway up the skimmer opening? If it’s too low, the pump will pull in air instead of water.
If needed, add water with your garden hose before you go any further. This is one of the most common and easiest to fix causes of a lost prime.
Step 3: Set the Valve to recirculate
If your pool has a multiport valve (the round dial on the filter), switch it to the Recirculate setting. This lets water bypass the filter and move through the system more easily while you’re priming.
If you don’t have a multiport valve, skip this step.
Step 4: Open the Air Relief Valve
On top of your filter tank, you’ll see a small valve or bleed screw. Turn it anticlockwise to open it. This lets trapped air escape from the filter as you fill the system with water.
Step 5: Remove and Clean the Pump Lid
Find the pump housing; it’s usually a clear or grey plastic lid on top of the pump. Unscrew it by turning it anticlockwise. Some lids have a ring you twist, others need a wrench.
Once the lid is off, pull out the pump basket. Clean out any leaves, hair, or debris that’s packed in there. A clogged basket is one of the top reasons pumps lose prime.
Check the O-ring too. This is the rubber ring that seals the lid. If it’s cracked, flat, or missing, air will sneak in every time. Apply a thin layer of pool lubricant to the O-ring, or replace it if it looks worn.
Step 6: Fill the Pump Basket with water.
Grab your garden hose and fill the pump basket all the way to the top with water. Do this slowly and completely. The more water you get in here, the easier it will be for the pump to re-prime.
Step 7: Replace the Lid Tightly
Put the basket back in, then screw the lid back on. Make sure it’s hand-tight. You should feel it seal. Make sure the lid is fully sealed, as even a small gap can allow air into the system.
Step 8: Turn the Pump Back On
Now power the pump back on. Watch the water flow through the clear lid (if yours is transparent). Within 30 to 60 seconds, you should see water flowing through the pump basket.
If you can see bubbles at first, that’s normal. Air is being pushed out. Once the bubbles stop and steady water flow fills the basket, your pump has found its prime.
Step 9: Close the Air Relief Valve
Once water (not air) starts spraying from the open relief valve on your filter, close it. This means the system is pressurised and water is moving correctly.
Step 10: Check the Pressure Gauge
Your filter has a pressure gauge on it. Normal operating pressure for most pools is between 8 and 15 PSI (some systems run a little higher). If the needle is in that range and stays steady, your pump is primed and running well.
Pump Still Won't Prime?
| Problem | Likely Cause | What to Do |
|---|---|---|
| Pump runs but no water flow | Air leak in suction line | Check all fittings and lid seal |
| Basket fills but empties fast | Skimmer clog or valve issue | Check skimmer basket and open valves fully |
| Pump hums but nothing moves | Motor or impeller problem | Call a pool technician |
| Pressure gauge reads 0 | Air still in system | Repeat priming steps; check O-ring |
| Water flows then stops again | Leak in plumbing | Inspect pipes for cracks or loose joints |
| Low pressure after priming | Dirty filter | Backwash or clean filter cartridge |
How Often Should You Prime Your Pool Pump?
Most pool pumps don’t need to be primed regularly. You’ll usually only need to do it in these situations:
- Opening the pool in spring after it’s been shut down for winter
- After a repair where water was drained from the system
- After a power outage that disrupted pump operation
- When the pool water drops too low from evaporation or heavy use
If you find yourself priming the pump every week, something is wrong. A pool technician can track down the air leak and fix it properly.
Tips to Keep Your Pump Primed Longer
A few small habits can help you avoid this problem in the future:
Keep your water level up. Add water when it drops below the midpoint of the skimmer. Low water is the #1 cause of a lost prime.
Inspect the lid O-ring once a month. A dry or cracked O-ring lets air in. Keep it lubricated and replace it once a year.
Clean the pump basket weekly. A full basket forces the pump to work harder and pull more air into the system.
Check for leaks around fittings. Run your hand along the suction-side pipes and fittings. If you feel air being sucked in near a joint, wrap it with Teflon tape or tighten the fitting.
Don’t run the pump with the pool closed off. Always make sure valves are open before turning the pump on.
Final Thoughts
Priming your pool pump is an essential skill that pays off every swimming season, helping you keep your water clean, your chemicals balanced, and your pool completely ready for a swim. By remembering to turn off the power, keeping your pool water level up, checking the lid O-ring, and filling the pump basket completely before restarting, you can easily handle this common issue on your own. Most pumps will successfully pull in water within 30 to 60 seconds of a restart.
However, if your pump still refuses to hold a prime after trying these steps, or if you suspect a deeper plumbing or mechanical issue, you don’t have to sweat it. Feel free to contact us today, and the Gator Pool Services team will get your system running perfectly in no time!