DE Filter Pressure Issues

by Mike
(Chapel, FL)

My saltwater DE pool filter starts out at 10-12 psi and moves to 30-35 psi with in about 30 minutes.

I have a 15' by 30' in ground pool in a house I just purchased a week ago. It was full of green algae and we have taken care of that issue but all of the grids in the filter were torn. Levels in the pool now are good but since the filter screens were torn, there was DE all over the bottom and sides of pool.

Here is what I have done so far:

- Equaled out the levels in the pool,
- Bought and exchanged all screens, Bought a Hayward XL pool vac,
- Back washed several times,
- I have also taken the filter apart numerous times and completely cleaned the new screens.

Now, I have not been putting new DE powder into the skimmer because it is all over the bottom and I assume that it will be sucked into the filter and stick to the screens itself.

After running my vac a bit, DE/sediment starts to run out the returns and coating the pool floor and walls again. I think, after reading some of your other replies, that may be due to the screen thing on the manifold keeps blowing off.

Everything seems to be fine until the pressure builds up, all returns run fine, vacuum and skimmer run great. When the psi hits about 32, the returns slow almost to a stop and a few minutes later, a high wheeze emits from the pump or filter. I have looks for leaks but I was unable to find any.

Let me know if I am doing anything wrong please and thanks!

Thanks for the question Mike

High pressure on a DE filter can be troublesome and sometimes hard to
pinpoint. The filter themselves are pretty straight forward. Thanks for looking over related questions on the Q&A page. Here are some I'd encourage you to review:

DE Filter Needs To Be Backwashed Every Hour

Too Much DE Filter Pressure

Pressure Builds Up In 30 minutes And DE Flowing Back Into The Pool

- A few things to consider: Be sure the pump motor impeller is not clogged. Turn the breaker off and the pump motor. Remove the pump basket and stick your fingers into the pump. The impeller should spin freely. Also be sure the gasket around the pump lid is good. If it's cracked, broken, squashed/squeezed, you need to replace it.

- Use a real DE scoop and not a coffee can. Using anything other than a DE scoop will give you either too much or too little DE.

- If you have a Multiport valve, check the spider gasket.

- Make a slurry of DE BEFORE putting it in the skimmer. Many people just dump the DE in. This can cause big chunks of DE sticking to the grids. If you shovel DE in the skimmer, it may not have a chance to coat the entire grid and you'll get uneven coating or chunks on the grids.

- And always be sure the grids are free of tears and/or rips. This is 99% why DE goes back into the pool.

I'd like to have your complete chemical readings:

Chlorine, CYA (cyanuric acid/stabilizer), pH, Alkalinity, Calcium Hardness, and Metals (iron and copper). It makes troubleshooting much easier.

If the issue is not a mechanical one, such as a clogged impeller or torn grids, algae might the the cause. Dead algae will clog up a filter pretty quickly, especially a DE filter because they catch almost everything.

Hope this helps and have a great Summer.


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DE Pool Filter Not Working

by Cynthia
(New Jersey)

We have back washed the DE filter, cleaned the rods and STILL the pressure is 30!!!

Not sure what else we can do.

Had a phosphate issue, that started this "fun" any thoughts?

Thanks for the question Cynthia

First I'll direct your attention to these posts. They're about high DE pressure issues:

DE Filter Pressure Issues

Too Much DE Filter Pressure

Use a real DE scoop and not a coffee can. Using anything other than a DE scoop will give you either too much or too little DE.

DE Pool Filters

DE Pool Filter Maintenance

Be sure the impeller is not jammed up with debris. Turn off the breaker, then the pump motor, remove the pump lid and the basket. Stick your fingers in the impeller and remove any debris.

The pump basket and skimmers should be cleaned out and no blockage.

Back wash the filter.

Check the pressure gauge and be sure it's working properly. Many times pool owners will get a false postive on low or high pressure because of a faulty gauge. Turn the system off. Does the needle drop to zero? If it does, the gauge works, if not, replace it.

Concerning your phosphate issue, well, don't be concerned about it. Phosphates are food for algae, but if you keep the chlorine between 1.5 - 3.5ppm and the stabilizer between 30 - 50ppm there won't be any algae, and that's what you want, no algae.

Here's a good post about that. It's a little long, but well worth the read. Be sure to read the comments as well:

High Phosphates Over 1000 & Cloudy Water

Check back to this post for updates or answers.

If you need immediate assistance (within 24 hrs) or for emergency personal assistance, you can make a donation of your choice and I'll answer your questions by phone.

Contact Me


Hope this helps and have a great Summer.


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No pressure, but only in return line

by Darren

I have a DR filter that I cleaned and reassembled. I have replaced the earth yet because I wanted to make sure water flow was alright. Problem I have is that the pump basket will fill as long as the backwash valve is open, but as soon as I close it to return the water to the pool, the pump basket quickly runs dry.

What would cause the suction to change when the outflow source from the filter is changed?

Hi Darren. Low suction can be caused by a few things. First would be to inspect the spider gasket in the multiport housing and replace if needed.

Next would be low water level in the pool. Maintain that between 1/3 - 1/2 up from the bottom of the skimmer.

Some other things to consider are:

  • Clogged pump and/or skimmer baskets

  • Clogged filter

  • Clogged impeller

  • Air leak in suction side - Check the o-ring in the pump pot lid

  • Water leak in the return side of the pump

  • Malfunctioning multiport valve

  • Hope this helps and have a great Summer.


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