Pool Filter Pressure Too High? 5 Important Reasons With Solutions!

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Why Is Pool Filter Pressure Too High?

Pool filter pressure too high, even after a backwash, can be both frustrating and confusing. It could be due to one of the 5 possible reasons below.

Fortunately, there are solutions! Go through the checklist below and you should be able to find the remedy, without the need of calling professionals.

Here is a table of common reasons & helpful solutions. Use the link in the table to jump to the specific section for more details.

Checklist of Common Reasons & Helpful Solutions

Reason	Solution
Improper Backwashing	Repeat backwashing and do it properly this time.

Sticky, Gooey Contaminants	Deep clean with a pool filter cleaner.

Unbalanced Pool Chemistry	Shock & Floc your pool. Then brush & vacuum.

Blocked or Faulty Plumbing	Locate, repair or replace faulty parts.

Old Filter Medium	Replace filter medium.

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1. Improper Backwashing

Silly as it may seem, it can happen. Maybe you were in a hurry and did not give the backwashing enough time. Maybe the pool pump did not generate enough pressure during the backwash. Maybe you forgot to rinse after the backwash.

Whatever the reason, the simple solution is to backwash the pool filter once again. This time properly. The proper way to backwash a sand or DE pool filter is as under:

Turn off the pool pump
Set the multiport valve (MPV) to “Backwash”
Turn on the pump

Backwash for 2 minutes or until the water in the sight glass is running clear
Turn off the pump
Set the multiport valve (MPV) to “Rinse”

Turn on the pump
Rinse for ½ – 1 minute or until the water in the sight glass is clear
Turn off the pump

Set the multiport valve (MPV) to “Filter”
Turn on the pump
Check the pool filter pressure

If the pool filter pressure stays around normal levels then the problem has been solved. If the pool filter pressure becomes high again go to the next step.

2. Sticky, Gooey Contaminants

The filter media, be it sand, zeolite, filter glass or DE, are pretty good at trapping all kinds of contaminants. Most solid contaminants are held loosely by the filter media and can be dislodged easily during the backwash.

Not hair oils, sunscreen lotions or strands of algae. These are sticky and gooey. They form bonds with the media or get entangled in the mesh. Backwashing can not dislodge them.

You need help from a pool filter cleaner.

The active ingredients in a pool filter cleaner are typically a combination of enzymes, natural bacteria and chemical agents that can break down the viscous contaminants and pry them away from the filter media.

Pour 8 oz of the pool sand filter cleaner liquid into the pool pump’s strainer basket. Run the pump for just 15 seconds or so. This is enough time to get the cleaner into the filter. Turn off the pump and let the cleaner get to work overnight. Backwash in the morning.

Now the backwash is able to eliminate them! With luck, the pool filter pressure will return to and stay at normal levels!

3. Unbalanced Pool Chemistry

Sometimes the problem may not even come from the pool filter. It can happen that your pool has been inundated with an unnatural level of contamination. Maybe it was torrential rains or a dust storm. Maybe it was a huge pool party.

Whatever the reason, such events can knock the pool chemistry, especially the sanitation level, completely out of the park. Bacteria and algae may flourish to abnormal levels. The pool filter starts clogging up. You backwash but after a little while the filter clogs again.

At this point you need to rebalance the pool chemistry. The first and the most critical step is to shock the pool. Shocking will neutralize the high level of pathogens, algae and other contaminants.

Next you must use a flocculant to coalesce the dead bacteria and sink them to the pool bottom. Use a pool brush to clean the sides and steps and follow that up by vacuuming the pool floor.

This is the best way to get the contaminants out of the pool without making them pass through the pool filter. Once the pool is clean, backwash the filter and you should be good to go!

4. Blocked or Faulty Plumbing

In addition to unbalanced pool chemistry, there is another set of extraneous factors that can result in making the pool filter pressure too high, in spite of backwashing. This has to do with blocked or faulty pool plumbing.

Honestly, this can be a little tough to isolate and rectify as the problem could, literally, be anywhere in the entire pool plumbing system. Some places and problems to look for are:

Backwash Valve Malfunction

Multiport Valve Broken or Leaking
Pool Pump Malfunction
Skimmer Blockage

Once you find the problem, clean, repair or replace the damaged or defective part.

5. Old Filter Medium

When did you last change the sand in the sand filter or the DE filter grid in the DE filter? If it has been quite some time then the chances are that it has outlived its functional life and needs to be replaced.

So now it may be time to change. Here is How To Change Pool Filter Sand? (An Easy 10 Step Guide!)

The actual life of the filter medium can vary based on contamination load, backwashing frequency, etc. However, you may use the following as a guideline.

Filter Media	Estimated Life
FairmountSantrol AquaQuartz-50 Pool Filter 20-Grade Silica Sand	3 – 5 years

ZeoSand, a Zeolite Pool Filter Media	5 – 6 years

Brightline 100% Recycled Swimming Pool Filter Media Glass	8 – 9 years

Pentair 59023400 Complete Element Grid Assembly Replacement	9 – 11 years