Your pool filter builds up pressure over time as it works hard to clean your water. As debris is filtered and more water is pumped in and out, the filter pressure can rise to dangerous levels. It is not impossible for DE filters to burst if left unattended.
Checking your pressure gauge often is imperative because high pressure can cause all sorts of problems with your pool. The ideal pressure range for a diatomaceous earth filter is around 8-10 psi (pounds per square inch). If you notice your filter pressure is rapidly surpassing this benchmark, then you will need to go through some basic troubleshooting methods.
How DE Filter Pressure Buildup Affects You
I have encountered pool filters with out-of-control pressure more times than I can count. It is a common problem that you are bound to experience, especially with DE filters. Essentially, high pressure is a sign that your pool filter is working harder than usual due to a system blockage or a malfunctioning filter part. When the pressure breaks the recommended threshold, your pool water will likely be less clean, and the filter may eventually need to be fixed. Fixing or replacing your DE filter can be extremely expensive, so I highly recommend keeping up with your DE filter maintenance routine. A well-maintained DE filter can last up to 25 years.
Your pressure gauge is your best friend, and frequently checking the reading can save you time and money. Remember, the ideal range is 8-10 psi. If you notice the gauge reading at 20 or even 30 psi, shut off the filter immediately and release the pressure. When the pressure starts to rise exponentially, the risk of the filter bursting is high.
Reasons Your DE Filter Pressure Is Rising Too Quickly
Pool filters are complex machines, so quite a few things can go wrong with them and cause the pressure to rise. When you notice that your DE filter pressure is going up rapidly, there is generally a simple fix. But I recommend learning all the possible reasons and solutions because you never know what can happen.
Here is a list of some of the most common causes of DE filter pressure buildup.
Dirty Pool Filter
Nine times out of ten, an unclean filter will be the reason your filter pressure is high. Dirty water is pumped into your filter, and the DE catches debris and algae on the filter grids. The debris will begin blocking the water flow in the filter, causing the pressure to rise. Air pressure from a dirty filter is inevitable and easy to fix. DE filters should ideally be cleaned out at least once a month, but clean as needed if you notice the pressure rising earlier.
How To Fix It
Release the pressure gauge, backwash and drain the filter, and clean out the filter grids. Remember to pull out each filter grid and hose off all the dirty diatomaceous earth. Replace all the components and replenish the DE.
Too Much DE Added To The Filter
When you change out the DE in your filter and add new DE to the skimmer, you will need to be sure to calculate the right amount of scoops. Generally, you will work out the square footage of your filter and divide it by 5. So a 20 square foot filter will get four scoops, while and 36 square foot filter will get seven scoops. You risk clogging up the filter grids if you add too much DE to the filter. Like a dirty filter, excess DE will block water flow and make the pressure in the filter rise.
How To Fix It
The only real way to fix excess DE is to clean it out entirely and start again. Although this will be expensive since you will waste an entire batch of DE, it is necessary to fix the pressure issue.
Pool Pump Is The Wrong Size
If you have recently changed your pool’s pump and you notice that the air pressure in the filter is rising more than normal, there may be an issue with the size of the pump. Your pool filter and pump should have a matching flow rate. If the pump is delivering a higher flow rate than the filter, the pressure will rise to dangerous levels.
How To Fix It
If your pump has a higher flow rate than the filter, you will need to replace it for your system to work correctly. If you are unsure how to find the right pump, talk to a pool professional to get expert advice. You can use my pool pump size calculator to get started.
Faulty Pressure Gauge
The issue does not always lie with the actual internal pressure of your filter. Sometimes you may be dealing with a broken pressure gauge. It can be super frustrating if this is the case. Personally, I have wasted lots of time trying to fix filter pressure when the problem was actually with the pressure gauge all along. Luckily, this is an easy fix once you determine that the pressure gauge is your problem.
How To Fix It
First of all, turn off your filter, and make sure that the gauge goes back to zero. The pressure gauge needle could have something obstructing it, or the mechanism could need replacing. I don’t recommend spending too much time trying to fix a faulty pressure gauge because they are cheap to purchase and easy to reinstall.
Check Your Breather Tube
The purpose of a breather tube is pretty much exactly how it sounds. It allows the filter to release the air trapped at the top of the filter. If the breather tube gets clogged up or damaged, it will not release air efficiently and cause a buildup of pressure in the filter.
How To Fix It
The first step is to check if the breather tube is the problem. Turn off the filter and release all of the air in your filter. Then open up the filter and check the tube. If you notice any cracks or damage to the tube, you should replace it. You should even replace a breather tube that looks old as they are easy to replace, and a new one can make a big difference.
If the tube doesn’t look damaged, check inside it to ensure nothing is clogging the airways. If there is some debris inside, give it a rinse and make sure everything is removed.
You should notice the pressure go back to normal if the breather tube was the culprit.
Diverter Valves Are Not Opened
Diverter valves are used to control the water flow in the pool. They usually have three openings that can be opened, closed, or partially closed. If the openings are closed to the return lines for extended periods, the pressure can build up in the filter.
How To Fix It
Diverter valves are super straightforward to use. If the pressure is building up due to the valve being closed or partially closed, you’ll need to open it back up. This should bring the filter pressure back to the right level.
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It is a scary sight to see your pool’s filter pressure gauge at two to three times the recommended psi. High pressure can lead to all sorts of damage to your expensive pool equipment and cause the filter not to run properly. The good news is you can quickly fix your DE filter’s pressure problems. And usually, the solution is just a standard cleaning. So there is no reason to freak out when you see your pressure rising. If you find that you need to replace your grids, read my article on how to replace DE filter grids. Follow my easy troubleshooting methods and you should have the problem fixed in no time!
Have any questions? Don’t hesitate to drop me a line!