Having crystal-clear pool water is what everyone wants when they decide to add a swimming pool. High pressure in your pool system can keep proper water filtration from happening. In extreme cases, high pressure can even be dangerous, since filter tanks have been known to rupture.
What is High Pressure?
We get plenty of emails from pool owners asking about high pressure in pools, what it indicates, and most importantly, how to reduce that pressure. Usually, pool owners want their problems solved easily so they can spend less time working on their filtration system and more time enjoying their swimming pool!
Pool filtration systems work by forcing dirty water into a filter, with clean, filtered water flowing out. Pressure pushes the dirty water through the filtration system, but there can be too much of a good thing where pressure is concerned.
Pressure levels can be monitored with the pool filter’s pressure gauge. Every pool system is different, so finding an exact number for “normal,” the number that has your filtration system running its best, is difficult.
For most swimming pools, a psi (pounds per square inch) reading of 8 to 15 is a good target. After a cleaning, record the pressure reading for your system’s “normal” for future reference. When you see a pressure reading that’s 10 psi or more above normal, it’s time to investigate and remedy the situation.
Why is High Pressure in Your Pool Bad?
Usually, a high-pressure reading on your pool’s filtration system indicates a problem with water flow.
Since pressure pushes water through the filtration system, a higher pressure reading means that the system is having to work harder to get dirty water through the system. It can indicate blockages such as a dirty pool filter, lime deposits, or broken parts inside the filtration system.
Other reasons for high pressure are that your filtration system is trying to filter more water than it can handle or that there is a suction air leak.
High pressure in your swimming pool means that your filtration is not working properly. Eventually, the result will be improperly filtered water and possibly the replacement of your filtration system.
Consider a high-pressure reading a warning bell that your swimming pool filtration system needs attention. Create the habit of checking your pressure gauge weekly as part of regular swimming pool maintenance, and you’re on your way to having a filtration system that’s always in top condition.
Causes of High Pressure and Quick Fixes
High pressure in your swimming pool’s filtration system can be caused by several factors. The good news is that most of them can be fixed quickly, easily, and inexpensively.
Check Your Pressure Gauge
First, make sure your pool filter pressure gauge is correct. Like all parts of a swimming pool’s filtration system, pressure gauges can and will wear out. If your pressure gauge is older or is cracked or damaged, consider replacing it. If there is no good reason why you are getting a high-pressure reading, your gauge may be the problem.
Replacing it is inexpensive and will save you from spending time and money trying to fix a nonexistent pressure problem in your swimming pool’s filtration system.
Dirty Pool Filters
Many times, a high-pressure reading indicates that it’s time to backwash your swimming pool filter. A dirty filter will impede the flow of water and will result in pool water that’s in less than optimum condition.
Pool filters don’t stay clean. Over time, the nooks and crannies of the filter cartridge get clogged with debris, chemicals, and oils from skin and sunscreens and lotions, and they can’t be hosed away.
Cartridge cleaners can help remove the gunk left behind. They can extend the life of your filter, but at some point, the cartridges will be dirty enough that replacing them is your only option.
For diatomaceous earth (DE) filtration systems, backwash them, and make sure to open the filter to wash grids and remove any debris. Sand filtration systems should be backwashed thoroughly. Replace sand as needed.
You may also want to check your filter’s media. In sand filtration systems, too much sand will slow the filtering of water through the tank, causing back pressure.
In diatomaceous earth systems, installing the wrong size of grid or using too much DE powder can also create higher pressure readings (read my guide on how much DE powder to add to your filter to make sure you add the right amount).
Using the wrong size cartridge or using one with less surface area reduces flow, causing another high-pressure situation.
Check the Air Relief Valve
The air relief valve can release air that gets into your filtration system. That air can cause pressure to rise, so make sure you release air through the air relief valve after maintenance such as cleaning or backwashing filters.
Suction Air Leak
Plenty of high-pressure readings are caused by suction air leaks before or at the pump level. Because of the air leak, more pressure has to be exerted to push dirty water through the filtration system. Over time, this will reduce the flow of clean water into the swimming pool.
Bubbles in the pump basket are a tell-tale sign that a suction air leak is the culprit. Another sign is seeing bubbles coming back into the pool from the returns. These signs can also help you pinpoint where the air is getting into the filtration system.
When you run a filtration system with air in it, water will compete with the air for space. The air must go somewhere, so it is forced inside the equipment. This can damage your equipment and especially your pump, which must contain water to work properly.
Clogged Breather Tube
The breather tube’s job is to release the air trapped at the top of the filter. Most pool filtration systems have a breather tube running from under the dome to the tank’s end. Some DE filters have built-in breather tubes that end at the discharge line.
In filtration systems that have breather tubes, air pressure at the top of the filter will build up if the breather tube becomes clogged. Also, check the breather tube for damage or small cracks. If you detect damage, the breather tube will need to be replaced for pressure to return to normal levels.
Oversized Pool Pump
A pool pump that’s too large for your pool will result in a high pressure reading for your filtration system.
Your swimming pool pump should be able to push all the water through the filtration system and back into the pool within about eight to 10 hours. More power than that, and you will have higher pressure readings. Having a higher horsepower than your pipes and filter can handle will mean that the pressure will build up after the pump.
Once the pump is turned off, the pressure will surge back through the pump, pipes, and into the swimming pool.
If your existing pump has multiple speeds, try operating it at the lowest speed.
Replacing the impeller with a lower horsepower version might take care of the excess pressure. Make sure to check on whether the diffuser should also be replaced.
The other option would be to replace the whole pool pump with one that’s the correct size. Use our pool pump size calculator to help you find the right fit.
If you need to replace your swimming pool pump, check the turnover rate to ensure a perfect match of the new pump to the existing filtration system.
Underfilled Swimming Pool
You might get high-pressure readings if the water level in your swimming pool is too low. This can allow air into your pool filtration system. Your pool’s water level should be at the middle point of the skimmer.
Closed Diverter Valves
A diverter, like its name implies, diverts the flow of water from one part of the swimming pool to another. If you have a diverter valve post-pump, it might have become closed to a section of return lines. This will cause back pressure in a filtration system. A partially closed diverter valve will also create a bottleneck for water flow.
If that’s the case, it’s the easiest fix on this list. Just open up the return lines.
Undersized Return Jets
Having return jets that are not large enough for your pool’s system will impede the natural flow of water, creating backpressure. If high pressure is a recurring problem, undersized return jets could be the cause.
Need Some Maintenance Help?
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Life has a lot of high-pressure situations to throw at you. Don’t let your swimming pool’s filtration system be one of them.
Regularly monitoring your filtration system will extend its life and result in clean, clear swimming pool water. Armed with this information, If you do see a rise in pressure, you’ll be able to track down what’s causing the pressure problem and make the fix.
Remember, your swimming pool is supposed to be an oasis of relaxation, not another source of high pressure in your life. We hope this handy guide to dealing with high pressure in your swimming pool filtration system will take the stress out of keeping your swimming pool in optimal condition.
Have questions? Let us know.