Correcting Low Water Pressure in Your Pool System
One day you come out to look at your pool and you notice that the water flow isn’t what it used to be. Your pool is cloudy or starting to get a tinge of green; your suction cleaner has stopped; your fountains or bubblers are barely generating columns of water; or you feel less water coming out of the return port. What happened and how do you fix it?
Many people equate low water flow to low system pressure. While it is true that many causes of low water pressure are due to low system pressure, low water flow can also be caused by high pressure. Pressure is typically measured at the pressure gauge on top of the system filter. This blog post will discuss causes of low water flow due to both low and high system pressure.
Causes of Low Water Flow Due to Low System Pressure
If your pressure gauge is showing a low reading and your pool is showing symptoms of low water flow, here are some of the probable causes:
Clogged skimmer basket
If your skimmer basket is full of debris, you are effectively shutting off the pipe between the skimmer and the pump. Generally this will reduce the flow of water to the pump. If less water enters the pump, the pump is moving less water out. This means the pump is doing less work that in turn will reduce water pressure.
Solution: Remove debris from the skimmer basket.
Clogged strainer basket
It is the same story as above. A clogged strainer basket means less water flow that leads to less water pressure out the returns.
Solution: Remove debris from the strainer basket.
Clogged suction pipe
A clogged pipe from the skimmer, suction line or main drain reduces the amount of water to the pump which can reduce water flow to the pump and create low water pressure out the return lines.
Solution: Push a plumber’s line down the skimmer or suction ports to see if you have a clog near the entrance. If there are no clogs there, you can try opening up the line before the pump to blow out the suction line backwards from the pump to the pool.
This problem is common, but 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“.
Too many features being used
The pump is only designed to move so many gallons per minute (GPM.) Too many water features are like too many hoses on a sprinkler system. The first one has great 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 the filter if you increase the pump’s horsepower.
Increased resistance (Head)
If you have just added a suction cleaner to your pool system, it may have increased the resistance to water flow to the pump. The hose adds another 30 or so feet to the piping which adds to total resistance. Also the hose is relatively small, ~1 ¼” diameter and ribbed which adds further to resistance.
Solution: Close off the main drain partially to provide more suction to the suction port.
Causes of Low Water Flow Due to High System Pressure
If your pressure gauge is showing a HIGH reading and your pool is showing symptoms of low water flow, here are some of the probable causes:
If water can’t get through a clogged filter, you will have less water flowing out of the filter. This will increase system pressure and reduce water flow. Solution – Clean/backwash the filter.
Solution: Clean/backwash the filter.
Too much sand in the filter
If your sand filter does not have a space of at least 6” between the top of the sand and the top of the filter, you will not be able to clean the sand sufficiently during backwashing and rinsing. The sand must be able to be lifted into this space during backwashing to loosen the debris out of the sand.
Solution: Remove the top layer of the sand to create a 6” space.
Too much DE in the filter
If you put too much DE into your DE filter, the grid will be coated too heavily restricting the flow of water through the grids. Restricted flow will increase system pressure and reduce water flow.
Solution: When you backwash your DE filter, only add back 80% of the DE powder. The filter retains about 20% of the old DE powder during a backwash.
Opposing back pressure
If your system develops an air leak on the suction side of your pump, air can collect in the top of the filter tank during operation. Over time this air will build up back pressure in the tank that will oppose the flow of water into the filter. Gauge pressure will go up and water flow will go down.
Solution: Correct the air leak. See our guide on “How to Identify and Correct Air Leaks“. Also check the air breather tube in your filter to make sure it isn’t clogged.
Too many return valves shut off
Make sure you have enough of your return valves open to balance the flow of water into and out of the system.
Hopefully this blog post provided you with enough information to isolate and correct the problem(s) with your pool’s low water flow. If not, give us a call at 877-372-6038 and one of our service reps should be more than happy to assist you. Have a good pool day!