High pressure in a pool filter usually means something is restricting water flow through the system. So, in most cases, the fix is to find that restriction and clear it.
Unfortunately, this can be easier said than done, as the pressure gauge only tells you there’s a problem — it doesn’t tell you what caused it. That’s why the best way to fix high pressure is to check the system in a clear order and rule out each possible blockage before the extra pressure puts more strain on the filter and plumbing.
In this post, we’ll explain what high pool filter pressure means, what can happen if it gets too high, and how to fix it step by step.
High pool filter pressure means water is meeting more resistance than usual as it moves through the filtration system. The pump is still pushing water forward, but something is making it harder for that water to pass through the filter and return to the pool.
Typically, this is due to a dirty filter, since trapped dirt and debris gradually reduce the amount of water that can flow through it. However, high pressure can also come from a closed or partially closed return valve, a blocked return line, a clogged return jet, or another restriction on the pressure side of the system.
A high reading is anything noticeably above a clean filter’s normal pressure. Since that baseline varies from one system to another, there’s no single pressure reading that applies to every pool.
That said, it can help to get some sort of starting point. So, as a general rule of thumb, if the gauge is around 7 to 10 psi above the clean starting pressure, the system usually needs attention.
Since it means the system has to work harder to keep water moving, several problems can happen when pool filter pressure gets too high, including:
If those problems develop, the system may stop circulating water properly or require repairs before it can run safely again. That’s why it’s important to identify the source of the pressure and fix it before the damage gets worse.
To fix high pressure in a pool filter, you need to check the system in a safe, logical order. Start with the gauge and filter, since they are the most common sources of the problem, then move on to the return valves and lines if the pressure stays high.
Here’s a step-by-step breakdown.
Before checking any part of the filter or circulation system, turn off the pool pump. This stops water from moving through the equipment and allows the pressure inside the filter to drop.
While you’re at it, it’s worth shutting off the power at the breaker for added safety. Remember to avoid loosening the filter clamp, removing the lid, or opening the filter while the system is running or still under pressure.
Check the gauge once the pump is off and the pressure has had time to drop. If the needle returns to zero normally, the gauge is likely working and you can move on to checking the filter.
However, if it stays above zero, the gauge may be stuck or damaged, which means the high reading may not be accurate. In that case, replace the gauge before troubleshooting the rest of the system.
Before troubleshooting further, note the clean starting pressure, so you have a baseline for comparison
Dirt is one of the most common causes of high pressure in a pool filter. As debris builds up inside, water has less room to pass through, which causes the pressure to rise.
So, clean the filter based on the type you have:
Once the filter is clean, put everything back together securely and check the pressure again. If it’s still high, move on to the next check.
Next, check the return side of the system. A partially closed valve or blocked return line can make it harder for water to leave the filter, which can build pressure.
Here, you’ll want to start by making sure all return valves are fully open and set to the correct position. Then check the return jets in the pool for weak or uneven flow. If one return has much less flow than the others, there may be a blockage in that line or in the jet itself.
If you’ve identified and corrected any obvious problems, restart the pump and give the pressure time to settle. If it returns to normal, you have likely cleared the restriction. If it stays high or begins rising again, the problem may be deeper inside the filter, plumbing, or circulation system.
If you’re still having problems after working through these checks, it may be time to have the system inspected. A professional can test the equipment under various conditions, isolate where the flow is restricted, and inspect parts of the filter or plumbing that are harder to access.
This can help pinpoint the cause without replacing parts unnecessarily or overlooking an issue that keeps coming back.
For help diagnosing and fixing pool filter pressure problems in Collingwood and the surrounding area, contact us at Clark Pools and Spas today.
