How to Prime a Pool Pump With Sand Filter

Even though Pool pumps now come with automatic priming that can save the pump from heating up or burning out there will be times that you will pull air in the system and lose the prime on your pool’s Sand Filter pump for different reasons that are discussed here in this article. If your pool pump pulls air, what’s the best way to prime a pool pump with a sand filter.


  • Turn off Pump-set multiport handle to recirculate
  • Open-air pressure valve-at top of Sand Filter-or loosen pressure gauge
  • Open Pump Strainer-clean basket-check O-ring for wear
  • Fill pump basket with hose-2-3 min.
  • Close lid-turn pump on
  • Wait for air to be released at pressure gauge
  • Close down
  • Set to filter


I used to hate vacuuming my inground pool because when I did, the Pool Pump on my Sand Filter always lost prime because the expensive vacuum hose had pin holes in it from wear, so I lived with it and managed to vacuum and re-prime my Sand Filter every week. There are other times when the pump loses prime for reasons that are unknown and need to be investigated.

Priming Pool Pump


Priming your Sand Filter’s pool pump could be as easy as filling your pump strainer with a bucket of pool water and reinstalling the lid then firing back up the pump and motor. But there are times when that won’t be enough to get the air out of your filtering system when it’s stuck or locked inside the return lines, pump, and sand filter.

Normally this will happen when you are vacuuming the pool, hooking and unhooking the hoses, or opening the strainer lid exposing the closed system to the atmosphere Other times it may happen for reasons that aren’t clear and need to be addressed.

Pool Pumps come with self-priming capabilities but can and do lose prime when air leaks open up and create problems for the normally closed systems. If this happens prime the pump and watch it carefully and if it happens again then you know that there is an active air leak in the system. Self-priming pumps need fluid in the casing to get started so even when down there should be some water inside. The first step to finding this is to prime the pool pump and watch the pressure gauge.


Priming the Pool Pump

  • Turn off the Pump
  • Turn the multiport handle to Recirculate on Sand Filter
  • Release air pressure valve- relieve excess air pressure in the lines by opening up the air relief valve located on top of the Sand Filter if no valve then open or loosen the pressure gauge
  • Open the Pump Strainer lid, clean the basket, and check the O-ring for damage
  • Fill the pump basket- use a garden hose to slowly fill the pump basket and put the lid back in place
  • Fill the basket and system lines and for 2-3 minutes-(watch for air forcing its way back out the suction lines being replaced with hose water)
  • Put the lid back on
  • Turn the pump back on
  • wait for the air on the relief valve to turnover to water at the top of the filter(this water will chase the air out of the system and prime the pump)
  • Turn off pump set to filter
  • Turn the pump back on




Sand Filters – Ask the Pool GuySometimes re-priming will work but other times this quick fix is not enough to get the air out of the Sand filter system and lines and you may have to look deeper into why or how the air is getting into the system.

This won’t happen and then just stop rather it will keep happening until you find out how air is getting in. You will need Pool water to chase the air out of an air-locked system to keep the pump running at 100 percent.

As pool water recirculates in the pool pump and forces air out of the pump’s discharge chamber, it’s trying to create an area of low pressure. If there’s an air leak in the suction line, air continues to be drawn into the pump, preventing it to release enough to create that area of low pressure. 

If there is no air release line, air cannot be vented to the atmosphere, and instead collects on the discharge side and locks up the filtering system and pool pump.

A lot of older Sand Filters don’t have an air release on the discharge side of the pump so you need to let that trapped air out by loosening the pressure gauge on top of the sand filter.


How to Get Air Out of Pool Pump


Most air leaks or priming problems happen on the suction side of the pool pump. The main reason your filtering system will accumulate air will be:

  • If the water in your pool is too low-If the pool water level is below the halfway point of the suction skimmers then there is a chance the pump will gulp air into the circulation system. If enough air is pulled into the system then the pool pump may lose its prime.
  • Not enough water in the pump strainer basket– Open the strainer basket and using a garden hose fill the basket and the lines for 2-3 minutes. Reseal strainer basket cover.
  • Clogged Skimmer or Strainer Baskets– clean out Strainer Baskets of any debris and return them to the skimmers


  • Pump Strainer leak- The pump will suck air through the gasket and will develop priming issues. Open and remove the pool strainer cover and pull the O-Ring gasket from the lid. Make sure the gasket is good by checking for cracking and replacing if necessary always lubricate the O-Ring with a silicone lubricant and reseat it properly inside the track on the cover. Replace the cover hand-tight do not over-tighten.
  • Check glued Connections-for cracks and integrity on the suction piping around the pump. Pour some water on the glued connections and see if any water is pulled inside the pipe. If so then you may have to repair the pipe connection.
  • Checked Unions-on suction side of the pump-take Unions apart and inspect O-Rings located inside for proper seating and damage-lubricate with a silicone product, reseat the gasket, and tape the threads on the Union with silicone with plumbers tape then hand tightened the connection.


  • Check the impeller on the pump- for debris that is obstructing the pump from filling the basket in the strainer and priming the pumps and the lines. If the eye of the impeller is plugged with debris, it removes the hydraulic capacity of the impeller to create an area of low pressure.
  • The pump speed is too low for the pump to prime the filtering system-If the pump has a low and high speed then it will have to be set to the higher speed in order to prime itself. If the pump is a variable speed motor then the pump can be set to a lower speed after its primed.




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JimGalloway Author/Editor


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