The most common reason your pool pump has high pressure is that your pool filter is dirty and restricting water flow.
The Main Culprit: A Clogged Filter
High swimming pool filter pressure is usually the result of a lot of particles being filtered out of the swimming pool water. As your pool filter (whether it's sand, cartridge, or diatomaceous earth - DE) does its job of removing debris, dirt, leaves, and other contaminants from the water, these particles accumulate within the filter media.
This buildup of filtered material creates resistance to the flow of water passing through the filter. Imagine pushing water through a clean sponge versus a sponge packed tightly with mud – the clean one offers little resistance, while the muddy one requires a lot more effort.
Understanding Filter Pressure
The pressure gauge on your pool filter or plumbing manifold typically measures the pressure the pump is generating to push water through the filter. When the filter becomes clogged, the pump has to work harder against the increased resistance to maintain flow, causing the pressure reading on the gauge to rise.
How to Address High Filter Pressure
Addressing high pressure often means addressing the clogged filter.
- Know Your Normal Pressure: You should know the "clean" or "baseline" operating pressure for your specific pool system when the filter is clean. This pressure varies depending on your pump, filter size, and plumbing. Keep a note of it. High pressure is typically considered 8-10 psi above this baseline.
- Identify the Issue: In most cases, a significant rise in pressure points directly to the filter.
- Clean Your Filter: Based on the type of filter you have:
- Sand Filters: When pressure rises it is time to backwash the filter if you have that option with a sand or diatomacesous earth (DE) filter. Backwashing reverses the water flow through the filter to flush accumulated dirt out to a waste line.
- DE Filters: Similar to sand filters, DE filters require backwashing to remove the clogged DE powder and debris. After backwashing, you typically need to add new DE powder to the filter.
- Cartridge Filters: These filters cannot be backwashed. When pressure rises, you need to remove the cartridge(s) and clean them thoroughly with a hose. If the cartridges are old or damaged, they may need to be replaced.
Other Potential Reasons for High Pressure
While a dirty filter is the most common cause, other issues can also lead to high pressure in your pool system:
- Closed or Partially Closed Return Valves: Valves on the return lines (leading back to the pool jets) that are closed can restrict water flow returning to the pool, causing pressure to back up in the system.
- Blockage in the Return Lines: Debris or obstructions lodged in the pipes leading back to the pool can create resistance.
- Restrictions After the Filter: Less common, but a blockage or restriction in the plumbing after the filter could also contribute.
- Too Many Return Jets Restricted: If you have multiple adjustable return jets and have significantly closed down the flow on most of them, it can increase back pressure.
- Incorrectly Sized Pump or Filter: Less likely to cause a sudden increase in pressure unless something changes, but an improperly matched pump and filter system can sometimes operate at higher-than-ideal pressures.
Checking Your Pool System Pressure
It's crucial to regularly check your pool filter pressure gauge. This helps you monitor the filter's condition and know when cleaning or backwashing is necessary.
| Condition | Pressure Reading | Action |
|---|---|---|
| Normal/Clean | Your system's baseline operating PSI | Continue normal operation |
| High Pressure | 8-10+ PSI above baseline | Time to clean or backwash the filter |
| Very High | Considerably above baseline / Red line | Stop the pump & troubleshoot immediately |
(Note: PSI ranges vary greatly by system. Always know your specific system's normal pressure.)
Next Steps When Pressure is High
If you observe high pressure:
- Turn off the pump.
- Check all valves to ensure they are in the correct position for normal operation.
- Determine your filter type (sand, DE, or cartridge).
- Perform the appropriate cleaning action (backwash sand/DE, clean/replace cartridge).
- Turn the pump back on and check the pressure gauge.
If cleaning the filter doesn't bring the pressure back down to its normal range, you may need to investigate other potential causes like valve positions or line blockages, or consult a pool professional.
