High Pressure Problem On A Swimming Pool Sand Filter

by Gina
(Swanzey NH)

We have back washed it several times and the pressure remains high. The filter is not strong anymore like when we first bought it. The sand and pump are only 3 weeks old.

We got sediment in our pool from running our well dry attempting to fill it and have been tryng to clean it ever since. We used flocculant and it was run through the filter before we read directions which stated to vaccuum it out through waste. Would that ruin the sand? The pressure is not high when we vaccuum through to the waste or backwash but is high on filter and recirculate. Do you have any suggestions on how to correct?

Thank you for your question Gina

First I would ask how the return water is to the pool and if that's normal? Your gauge should be reading an increase and the water flow to the pool should decrease as the filter gets dirty. If the flow rate is strong, the issue might just be a faulty gauge.

First check to see if the gauge goes down to "0" when the system is off. If it doesn't, the problem may be a faulty gauge and you'll need to replace it. If that is not it, run the pump with the Multi-Port Valve "recirculate" position and see if it makes a difference in the flow rate back to the pool or a difference in the gauge reading. You should see a small difference here.

If you still have the problem, it's not a problem in the filter tank, it might be some kind of blockage in the lines. If this does cause the pressure reading to drop back to normal, there may be some internal damage inside the tank (but you might have been able to see this when you changed the sand.) Knowing the make and model number would be helpful in troubleshooting.

Filter sand normally needs to be replaced only once every 3 to 5 years, sometimes more depnding on the usage, but it should not cause the problem that you're having after only after a few weeks, unless the filter was really clogged up with debris for some reason. Be sure the bottom drain, skimmer(s), and pump motor basket are all free of debris.

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.

If you've found this site helpful please consider making a donation. Thank you.

Hopefully these troubleshooting tips will help you

Best of luck


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Pressure Building Up In Filter

by Noel
(Perth WA)

I have a Emaux MFV27 sand filter.
When the pool cleaner is connected within 15 minutes the pressure builds up from 60KPA to 110KPA. Filter normally runs at 60KPA.

I have replaced the MPV and top tank and also done a sand change. And the pressure still builds up. I contacted the company and they said to use a more coarse sand on the bottom of the filter. So I have done a second sand change in the past two weeks and still have the same problem. Can you please advise.

Thanks for the question Noel

From what I'm reading the question says the pressure is fine and in range before you attach the cleaner. Can I assume it's a suction cleaner such as a Barracuda or Kreepy? You then attach the cleaner and within a few minutes the pressure rises. Is this correct?

If it is, then from what I can gather the only piece that's added to the puzzle is the cleaner itself. I would encourage you to check the line to be sure it's free of debris and check the cleaner. It may be clogged with debris or some other foreign matter that's restricting water flow back to the pump.

High pressure normally results from some restriction on the suction side. This can be narrowed down to the bottom drain and/or skimmer. Also be sure you have the right amount of sand in the filter. This is known as freeboard and is the measurement between the top of the sand to the top of the filter. Your owner's manual should have that info. Top off with an inch or two of sand if needed.

You can also check the PSI gauge to be sure it's working. Simply turn the system off and check if the needle drops to 0. If it does turn the system back on and if the needle jumps up to the right pressure then it's good. If when you turn the system off and the needle sticks the gauge is bad so you need to replace it.

I hope this has answered your question to your satisfaction.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Sand Filters" category.

Check back to this post for updates or answers.

If you feel your situation is more complex and want immediate assistance (within 24 hrs) you can make a donation of your choice and I'll answer your questions by phone.

Have I helped you find a solution to your pool problems? Did this information help you? Please consider making a donation to help keep this site going. Thank you.

Have a great Summer.


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The Hayward Sand Filter

by Brenda Edwaards
(Bedford Area)

When I turn pump on the pressure causes the pump basket cap to throw water back out. It has two indentions cut made in cap tp fit in two groves Is there some kind of magic into screwing these two together that I am not doing? I just got this nice 1500.00 sand pump from a friend I want to use it. It is about five or more years old also I have an above ground pool wants some pictures how to improve looks around it.

Thanks for the question Brenda

No, there's no magic in getting the plastic pump pot lid back on, if that's what you're referring to. There should be 2 - 3 notches around the black part of the lid. You need to align those up with the inside clear plastic part, then twist to get a good seal.

You may not be getting a good seal due to the o-ring. Replace if that's cracked or broken.

If you feel your situation is more complex than this, I do phone consultations. It makes things go much faster and many people have found it extremely beneficial, saving them time and money in the long run. All your questions will be answered. I have nothing to sell you so you know I'm not bias.

Pool Consultation

Hope this helps and have a great Summer.


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Low Flow At The Pool Return

by Mike Bass
(Lillington NC)

I just opened my pool from the winter. I started circulating the water with my multi port Hayward sand filter really after I added some chemicals. After circulating, I back washed and rinsed the filter. I set it to filter and everything was running great. After a couple hours, I noticed very little water flow coming out of the return. I tried back washing again and flow was great. Then, again, the flow in the return dropped to a very low flow.

Note; after back washing, the gauge read 18 which is normal for my system. When the flow had dropped, the pressure had jumped to 21. Not to high but higher than normal. I've tried back washing several times, but the same thing keeps happening.

Hi Mike. There could be one or a combination of things that can cause low flow from the returns. Here are some places you can start.

The suction side - Be sure the pump and skimmer baskets are clean, and the bottom drain. Valves should be partially or fully open, depending on your situation and pool's needs. Next, check the pump lid and gasket and replace if cracked or broken. Check the pump impeller for blockage and remove any debris. Be sure the impeller spins freely. The 90s going into the pump pot sometimes can get clogged with debris or leaves which can cause low flow. If the pump pot is cavitating or the water is churning, there's a suction side blockage.

Return side - Be sure the filter is cleaned out. Check if there's enough sand in the filter. This is called freeboard. It's the measurement from the top of the sand to the top of the filter. The multiport valve should be working correctly. The spider gasket might need to be replaced.

All o-rings on both suction and return side must be intact and replaced if needed.


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