Low water pressure is a pool term often used to describe weak jets and a low PSI reading on the filter’s pressure gauge. Low pool filter pressure is a common issue that contributes to these symptoms, often resulting from blockages before the filter or potential leaks in the pool system. High PSI readings will also cause low water pressure. Weak jets, air bubbles, slow pool cleaners, and weak water features show low water pressure. This guide addresses the common causes of low water pressure in a pool.
Things You’ll Need
Step 1
Your pool’s plumbing system can be broken into two sections: the suction side and the pressure side. The suction side of your pool includes the skimmer, main drains, plumbing, and any other equipment, like diverter valves, up to the strainer housing of your pool pump, including the pool pump basket. A clogged or full pool pump basket can restrict the flow of water to the pump, leading to low water flow and pressure.
The suction side is the portion of the system where your pump pulls the water toward it. A full or clogged pump basket can significantly restrict this water flow, contributing to low water pressure issues.
The Pressure of your pump begins at your pump’s impeller when the pump’s pulling becomes a pushing force to move the water through your pool filter, heater, chlorinator, and all the associated plumbing until it returns to the pool via the return jets.
Step 2
Low Water Level - The water level should be halfway up the skimmer door opening. A low pool skimmer water level will allow the skimmer to gulp air as your water ebbs and flows due to the pump running or activity in the pool.
Step 3
Clogged Skimmer Basket (Low PSI) - If your skimmer basket is full of debris, you effectively shut off the pipe between the skimmer and the pump. Generally, this will reduce the flow of water to the pump. If the pump has less water entering it, it is moving less water out. This means the pump is doing less work, which, in turn, will reduce water pressure.
Solution: Clean your skimmer basket by removing any debris.
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Step 4
Clogged Strainer Basket (Low PSI) - It is the same story as above. A clogged strainer basket means less water flow, leading to less water pressure from the returns.
Solution: Clean your strainer basket by removing any debris.
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Step 5
Clogged Pool Filters (High PSI) - When water can't get through a clogged pool filter, including DE, sand, and cartridge filters, less water will flow out of the filter. This situation increases the filter's water pressure, signaling it is time for regular maintenance and cleaning to maintain optimal water flow and pressure. Monitoring and maintaining normal pool filter pressure is crucial for the health of your pool's filtration system.
Solution: Wash your cartridge filter. Periodically soak the filter overnight in a TSP solution to remove body oils and gunk from the folds. Grease is produced by suntan lotion, sebum (oils secreted by the human body), and pine tree needles. Then, soak the cartridge in a weak solution of muriatic acid (10:1) to remove minerals from the folds. Use the TSP before the acid, or the gunk will be set in the folds. For sand filters, it's essential to backwash them as required to prevent clogs that can lead to increased filter pressure. Change the sand every five to seven years. In between changes, if sand has caked on top, remove one to two inches off at the top and replace it with new sand.
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Step 6
Clogged Impeller (Low PSI) - This problem is often overlooked. If the impeller becomes clogged with debris, water can't rotate out the sides of the impeller. This decreases suction, which reduces water flow through the pump.
Solution: Clean out the impeller. See our guide on "How To Clean Out a Pool Pump Impeller."
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Step 7
Suction Leak At Pump (Low PSI) - The pump lid o-ring, pump intake fitting, and drain plugs are common areas to draw in air. A suction leak in the suction side of the pump can cause several problems. If it's large enough, too much air will be sucked into the system, and the pump will lose its prime. If it's smaller, air will be sucked in through the pump and start to collect at the top of the filter tank. After some time (sometimes a few hours), the air pressure at the top of the tank will create enough back pressure to reduce the water flow significantly. When the pump is shut off, this back pressure will cause the water in the suction pipe to surge back and sometimes create a column of water up through the skimmer.
Solution: Find the suction leak and close it. See our guide on "How to Identify and Correct Air Leaks".
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Step 8
Suction Leak at Diverter Valve (Low PSI) - The diverter valves in front of the pump control water flow from the skimmer, main drain, and vacuum lines. They also have seals that can go bad and allow air to enter the system. Again, air will cause the water pressure to drop, leading to the pump losing its prime.
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Step 9
Suction Leak At Plumbing Fittings (Low PSI) - Any fitting on the suction side of the system can draw air. Cut out and replace any fittings that have an air leak.
Step 10
Clogged Pipe Going To The Pump (Low PSI) - A clogged pipe from the skimmer, suction line, or main drain reduces the amount of water to the pump, reducing water flow to the pump and creating low water pressure out the return lines.
Solution: Push a stiff wire down the skimmer or suction ports to see if you have a clog near the entrance. If there are no clogs, you may have to get a pool professional to check your pool pipes. Regular maintenance and checks are crucial to prevent clogs that can affect water pressure and the performance of the pool filtration system components.
Step 11
Too Many Features Opened - The pump is only designed to move so many GPM. Too many water features are like too many hoses on a sprinkler system. The first one has tremendous pressure. Subsequent hoses will reduce the water pressure.
Solution: Alternate which features are turned on or replace the motor in your pump with a larger one. Make sure your existing filter will support the larger pump. You may also have to replace it.
Step 12
Pump Is Too Small - If your pump's size was calculated for your initial pool system and you have added more equipment to that system, you may have exceeded the pump's capability to supply the GPM that is now required. Also, if you have moved your pump significantly further away from the pool, which requires more pipe, you may have increased water resistance in the pipes that exceed the pump's capability.
Solution:
- Replace the motor in your pump.
- You may also have to increase your filter size if it doesn't handle the increased GPM water flow.
- See our guide on "How To Replace the Motor on Your Pool Pump."
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Step 13
Bad Pressure Gauge - Pressure gauges on the filter can go bad. Your apparent low-pressure reading may be due to a faulty gauge.
Solution: Replace the pressure gauge. See our guide on "How To Replace a Pool Filter Pressure Gauge on a Cartridge Filter."
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