How To Backwash a Pool Sand Filter

Written by:  Danny Rhodehamel
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 (3.5 OUT OF 5 STARS ON 11 RATINGS)

After a period of time, the contaminates in a sand filter start to clog the sand to the point where water flow is significantly diminished and the pressure gauge rises 8 to 10 psi above normal operation readings. To clean out the contaminates, you have to backwash the sand. This guide shows you the steps in backwashing a filter.

Tips & Warnings

Video

Step by Step

Step 1

To prevent damage to the plumbing or valve you must first TURN OFF THE POOL PUMP before moving the multiport valve handle. For maximum safety turn off the power at the circuit breaker to the pump.

Step 2

Your pool filter valve is probably at the FILTER setting for normal operation. Depress the multiport valve handle and move it to the BACKWASH setting. To prevent damage to the multiport valve seal, always depress the handle fully before turning.

Step 3

Make sure your WASTE hose is laid out to where you want to dump the waste water.

Step 4

Turn the power back on and run the pool pump for at least 2 minutes. The water in the sight glass on the side of the valve will change from cloudy to clear.

Step 5

Turn the power back OFF.

Step 6

Depress the multiport valve handle and turn it to the RINSE setting. After backwashing, the sand is loose and needs to be reset. Also any dirty water from backwashing has to be rinsed out of the filter to WASTE to prevent it from returning to the pool.

Step 7

Turn the pump back ON and run filter at the RINSE setting for 1 to 2 minutes.

Step 8

Turn the Pump OFF. Depress the multiport valve handle and turn it to the FILTER setting.

Step 9

Turn the pool pump ON for normal filter operation. Check your pressure gauge to ensure that the pressure has dropped 8 - 10 psi from where it was before backwashing the pool filter.

Comments (1 to 40 of 172)

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User: Inyopools

first time - Check the spider gasket in your multiport valve. It may be damaged and may be diverting water to the wrong place. See our guide on "How to Replace a Spider Gasket on a Multiport Valve".

User: Inyopools

From Dan - While Dan was waiting for a response, he was able to fix his problem himself and was good enough to provide this feedback. Thanks Dan.
"I got it fixed I took the pipe and fingers back out of the sand filter and found a crack in the bottom of the hub, replaced the hub, and cleaned the fingers and put back in. Working like a charm."

User: first time

Whenever I vacuum to waste, I was having a hard time getting my pump to prime when I turn it back to filter. I had it working, but just started to backwash and no water was coming out. Any suggestions are welcome!

User: dan

don't have a air tube it is a dream line sand filter system with a Haywood valve I can cot it off and mash down on the valve and let about a gallon of water out the waste and turn it back on and does good for a hour or so then same thing again

User: Inyopools

Dan - You may have backpressure building up in the top of your filter. If your filter has a breather tube from the bottom of the tank to the top, see if that tube is clogged. If it is clogged, it is not able to relieve trapped air in the tank.

User: Dan

Start up season 15 x 30 above ground pool No problems last year Now it runs and does good for a couple hours then pressure goes to 20psi from 10psi and flow slows way down in pool.Changed sand,cleaned propeller,back-washed and rinsed Then starts back up good and after a couple hours does same thing.Water cloudy but not green Not dirty 175lb sand filter Hayward pump and valve????

User: Inyopools

leaking backwash - You may have a damaged spider gasket in your multiport valve. See our guide on "How to Replace a Spider Gasket on a Multiport Valve" to inspect and possibly replace this gasket.

User: 

After backwashing and putting value back in the filter position turn the filter back on sometimes the pressure builds up and water come out the backwash hose

User: Inyopools

Mimzie - Nothing is wrong. 10 psi is a good reading for an operating sand filter.

User: Mimzie

I just purchased a house with a inground pool and I have the sand filter and it stays on around 10 psi while running on filter. is that correct or is something wrong?

User: Inyopools

HELPLESS - You may have damaged the spider gasket in your multiport valve. To look at this gasket and possibly replace it, see our guide on "How to Replace a Spider Gasket on a Multiport Valve".

User: HELPLESS

I am new to the pool ownership world and I may have messed up. I was cleaning my inground pool and forgot to turn off the pump before switching my sand filter to backwash. Now I can't get the pump to prime. When I fill up the pump with water it just flows back to the pool and skimmer, I can plug the skimmer and the pump will fill but I know that's not correct and the pump does create pressure but my system doesn't have a gauge. Just trying to figure how to get my pump to prime again? thanks!!

User: Inyopools

Cfran20 - Not sure what's going on here. As you say, a 4 psi rise should not shut done your system. Sand is only 1 year old so should not need to be replaced. Your filter is sized correctly for your pump. Is this happening at the lower pump speeds which may be more susceptible to clogged filters? Check that there is at least 6' of space between the top of the tank and the top of the sand. Also run your backwash / rinse cycle 3 times in a row to make sure your sand and laterals are clear.

User: Cfran20

Hello, great video!! I have a Hayward sand filter with 350lbs of sand and a 1.5 hp ecostar Hayward pump. Normal pressure is at 18 psi and has been since installed last October. When pressure reaches 22 psi there is so little water moving you can't really tell the pump is running, once I back flush it drops back to 18 and runs fine. Replaced the gauge to see if that is the issue and same issue. Should a rise in 4 psi be enough to basically shut down flow? You reference a min of 10 psi before back flush is needed several times. Thanks for your help.

User: Inyopools

Jimmy - Depending on pool use and backwashing, the typical life of sand in a sand filter is 5-7 years. However, as your pool store indicates, as long as your pool is not turning green and the period between backwashing is not decreasing, your filter's sand is probably good for another year or so.

User: Jimmy

My pool store told me that sand, depending on specific conditions, can last 5 to 15 years before it becomes worn out. They said the way to tell is check for a pressure increase of 8 to 10 psi over time (and backwash with this increase). If i'm getting this pressure rise and the backwash water is dirty, the sand is GOOD and doesn't need replacing. They say the pressure rise means the sand edges are not rounded badly and I'm still trapping debris. Is that information correct? My sand is about 8 years old, but I am getting the pressure rise and NOT wanting to replace the sand prematurely.

User: Cfran2020

Hello, great video!! I have a Hayward sand filter with 350lbs of sand and a 1.5 hp ecostar Hayward pump. Normal pressure is at 18 psi and has been since installed last October. When pressure reaches 22 psi there is so little water moving you can't really tell the pump is running, once I back flush it drops back to 18 and runs fine. Replaced the gauge to see if that is the issue and same issue. Should a rise in 4 psi be enough to basically shut down flow? You reference a min of 10 psi before back flush is needed several times. Thanks for your help.

User: Inyopools

Mugsy51 - No, there is no lock on the valve that you have to release to depress the handle. Sounds like something is stuck inside the MPV. Try taking the top assembly off of the MPV like you would do to replace the spider gasket to see what might be binding the handle. See our guide on "How to Replace a Spider Gasket on a Multiport Valve".

User: Mugsy51

I've watched your demonstration many times since I have to backwash my Pentair Triton II sand filter for the first time. In your presentation and others it seems like people just push down on the multiport valve and it goes down. I've been trying all afternoon with all my weight, but it just won't budge. Is there some kind of latch or do-dah to fiddle with first?

User: inyopools

louie4 - Sounds like it's time to change your sand. Sand should be changed every 5-7 years. And if the standpipe assembly came up, you will have to pull the sand out anyway to reset the assembly.

User: louie4

My Hayward sand filter is 6.5 years old. I backflush it regularly, but it doesn't seem to get itself clean anymore. There is no change in the pressure drop. Always about 28-29 psi. Thinking I had built up a layer of impermeable debris on top of the sand, I took the top off. Not much debris there. But the standpipe assembly came up through the sand with the top. Now what?
Is it time to drain the filter and replace the sand? Or just figure out a way to get the standpipe back down?

User: Espocom

8-8-2015 My compliments to you on the way you have your website set up. I watched your "How To" on back-washing a sand-filter and found it to be very, very helpful. I'll certain purchase items on-line from you as I get better, more accurate information from your site than the high school kids behind the counter at my local pool store. Thanks again!

User: Inyopools

caitlin - If your filter gauge never showed pressure before and is now stuck on 22 psi before and after backwashing, I would guess that your pressure gauge is bad. And this filter has not air relief valve. Air bleeds naturally through the sand.

User: caitlin

THE GAGE ON OUR POOL IS SHOWING 22PSI BUT IT HAS NEVER SHOWED ANY PRESSURE BEFORE WE BACKWASHED IT EARLIER BUT NO CHANGE IN PSI THE POOL IS ONLY 2 YEARS OLD ANY IDEAS ? IS THERE A AIR RELIEF VALUVE ? MY PUMP IS A CAREFREE WATERWAY SAND PUMP ?

User: Inyopools

Sandrosko - 30psi is high for a sand filter. If you vacuumed a lot of debris through your filter you might try backwashing /rinsing 3-4 time to remove the debris from the sand. If you haven't replaced your sand in 5-7 years, it's time to replace your sand. Your pump may be too large for your filter. The filter size should be large enough to at least handle the GPM water flow generated by your pump. I'd recommend a size larger than required for a buffer and to the time between cleanings.

User: Sandrosko

The pressure during normal filtering had been running at 30psi. When I back wash after vacuuming, water shoots out of the sight glass like a fire hose.

Any ideas?

User: Inyopools

Deeno - If your Mutiport valve is in Waste mode and you forget to open the Ball valve on your waste line, water flow will stop. Any air in the system will be compressed and may blow gaskets. The motor will be running with no water flow to cool it and it will overheat but hopefully shut off through the motor's overload protector.

User: Deeno

Can you tell me what would happen if when you backwashed, you forgot to open the waste valve? Would contaminates somehow go back into the pool because of pressure, or would the sandfilter blow before that happened?

User: Inyopools

Steve - You did not damage your sand filter. When you are in rinse mode, the water is directed down through the sand and up through the standpipe just like in filter mode, but instead of going back to the pool for "filter", it is directed out the waste port during "rinse". See our guide on "How a Multiport Valve Operates".

User: Steve

I accidently vacuumed my pool in the rinse setting. Could I have damaged the sand filter?

User: Inyopools

backwash - You would leave all the valves open for backwash the same as if you were in filter mode.

User: 

Hello, before starting a backwash, do i need to close the main valve to the pool, as in when i clean the skimmer box? or do i leave all valves open along the system?

User: Inyopools

swimmerjane - Sounds like the capacitor of your motor is failing. See our guide on "How To Replace a Pool Pump Capacitor" for more information.

User: swimmerjane

Hello there. If we turn off our pool pump for any reason It is difficult to get it to restart. It will hum for about 10 seconds and then shut off. It will reattempt after a few minutes. Sometimes it will engage most times it does not and it will throw the breaker. My husband believes that because we had the skimmer clogged with leaves a couple of times when we were away, it damage the pump. We have the pool pump on a timer to turn on in the morning and off in the evening. Our dealer suggest that this could be hard on the pump - the starting and stopping. Ideas, suggestions?? Pump is only three years old.

User: inyopools

bren A - If you changed anything on your system after last year, look at those changes and make sure they were done correctly. If this is an above ground pool, do you have one of the shut off valve closed preventing water from getting to the pump. If this is an in-ground pool, make sure your diverter valves are set correctly so you have an open path to the pump.

User: bren A

I can't Backflush I get nothing. When I turn back to normal filltration I get nothing again nothing. It was renning perfict last year. It seems the names on the circle indercater is wrong what can I do.

User: Inyopools

Courtney - The normal psi for a Hayward Sand Filter is 10-15 psi. You would normally backwash the filter when the psi is 10 psi higher.

User: Inyopools

New2Pools - Yes water is suppose to flow out of the waste hose on a rinse cycle. See our guide on "How a Multiport Valve Operates" for more information. Question #2 - I would patch the hole in the liner to make sure it doesn't get bigger. Here's a link to our "EZ Patch 28 - Vinyl Pool Liner Repair Sealant".

User: Courtney

What is a normal psi for a Hayward Sand filter and when should I perform a backwash?

User: New2Pools

2 questions....#1-Is water supposed to come out of backwash hose during rinse cycle?.....#2-Have a hole in top of liner, should I be worried about rain water getting in there?

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Tips & Warnings

Don't backwash excessively. Contaminates in the sand actually help the filter work more effectively - to a point. Monitor your pressure gauge for an 8-10 psi rise.

Never move the valve handle when the pump is on.

Don't vacuum your pool in backwash mode. You may clog the collection pipes (laterals) at the bottom of the filter.


Please Note:

Inyo Pool Products is not responsible for any injury or damaged equipment
while using our guides. Using our guides is doing so at your own risk.
These guides are suggested use of your pool or spa equipment and may vary
depending on which product you are using.