How To Backwash a Pool Sand Filter


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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.

Click Here to View Replacement Sand Filters

Click Here to View Replacement Parts for Sand Filters 


Step by Step


Step 1

Turn off power to your pool pump at the circuit breaker. To prevent damage to the valve, or any other pool equipment always turn off the pump before moving the multiport valve’s handle

Step 2

Depress the valve’s handle and turn it until the selector notch points to BACKWASH, then release the handle.

Tip for preventative maintenance: Always turn your valve’s handle the same direction when changing settings; either always right or left. Do not turn opposite direction even if the other way is a shortcut to your desired setting. This reduces chances of uniting the spider gasket and undue wear and tear.

Also, make sure the handle is fully depressed when turning the selector handle.

Step 3

Make sure Waste hose is securely connected to the valve, and free of kinks to allow for free flow to your desired drainage point.

Please Click Here to View the Backwash Hose

Please Click Here to View Hose Clamps

Step 4

Turn on the pool pump breaker, then turn on the pool pump. Let the pump run for about two minutes or until the water in the sight glass is free of silt. 

Note: If you’re planning a longer than normal backwash and rinse due to an excessively dirty filter, set you suction diverter to only pull water from your main drain. Making this change will prevent your pump from losing prime or running dry if the pool’s water level drops below the skimmer.

Step 5

Turn off the pump again

Step 6

Set the valve to Rinse. Depress the valve selector handle, then turn it to the Rinse setting. After a backwash, sand and debris becomes unsettled settle in the filter’s internal plumbing. The rinse setting returns to the normal path through the filter, flushing debris to waste.

Step 7

Turn the pump on, let it run for about a minute or until the sight glass is clear of silt and sand.

Step 8

Turn off power to pump to set the valve selector handle to its normal Filter setting.

Step 9

Turn on the pump to resume a normal filtering schedule. Check your pressure gauge to ensure the system’s pressure has returned to your pool’s normal “clean” PSI range.

Please Click Here to View Pressure Gauges.

If you experience issues after backwashing, here is a list of helpful how-to guides for troubleshooting:

How To Determine Why a Pool Pump Won't PrimeSand in Your Pool?

How to Reduce High Pressure in Your Pool System

How to Correct Low Water Pressure in Your Pool System


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InyoPools Product Specialist  Posted: 8/15/2013 

Mikedb007 - When you used the "Filter " setting, you probably "set" the sand like you would have in the "Rinse" setting except the rinsed water went back into the pool instead of the waste line. It won't hurt to "rinse" the sand again but you may be past that point. If you can, try vacuuming any debris in the bottom of the pool to the waste line, otherwise keep running in filter mode until the debris is filtered thru the filter.

 Posted: 8/15/2013 

Thanks for your How-to. I wish I read it before and not after backwashing for the first time.
The pool is not new but we are new owners. It has a Hayward sand filter with top-mount multi-port valve.
I missed the rinse step after backwashing and went straight back to filter(at least I know enough to shut pump off while switching settings). Well we wound up blowing sand and other dirt back into the pool. I have vacuumed on filter setting but it still seems cloudy. I am unsure whether I should be running it on rinse now to set the sand or if it is too late for that. Any ideas on what I can do to get the pool clear in a hurry(supposed to have family over tomorrow for pool party) and do I need to do anything with the pump/filter to make sure it is working properly? Thanks in advance for your help.


InyoPools Product Specialist  Posted: 8/12/2013 

MPV sequence - That is correct. After vacuuming on waste, clean out any debris in the pump strainer basket and return to the filter cycle. You do not have to backwash because the debris bypassed the filter and went out the waste port.

Anonymous  Posted: 8/11/2013 

Hi after vacuuming on waste, do I just empty the drain basket or skimmer I think it's called and go directly to filter after powering off and disconnecting the vacuum and hose?

InyoPools Product Specialist  Posted: 7/18/2013 

justkeepswimming - Try taking the vacuum off and trying to run the pump in either filter or backwash mode to see if that primes the motor. If not, look for leaks on the suction side of the pump. See our guide on "How to Identify and Correct Air Leaks". If the pump does prime, look for leaks around the suction cleaner hoses.

 Posted: 7/17/2013 

Hi, so I was wondering if I could have your help as well. So I have had my pool for a couple of years now and I got a new pump about a year ago. I got a Hayward Sand Filter and its been doing fine up until recently. There was so much alge in our pump sand we replaced our sand. Then recently we've been trouble it pumping right. We backwash it and we run our vacuum Wanda the Whale and now it won't pump and we can't get it to prime. Please help. Thanks

InyoPools Product Specialist  Posted: 7/4/2013 

newtopool - Either main drain or skimmer or both is fine. In backwashing you are just reversing the flow of water through the filter - up through the sand instead of down. It does not matter where the pool water comes from.

 Posted: 7/4/2013 

Should the pool be set to main drain or skimmer when backwashing?

InyoPools Product Specialist  Posted: 6/29/2013 

Romegero - There is nothing in the Owner's Manual about waiting a 1/2 hour after Rinse. It just says go to Filter. One of the purposes of the Rinse cycle to repack the sand under water pressure. I don't think sitting for a 1/2 hour without pressure will do much more. And thanks for the suggestion to move Step 6 up in the sequence.

 Posted: 6/28/2013 

First, the current Step 6 "Make sure your WASTE hose is laid out..." should probably follow Steps 1 or 2.

My main question relates to a statement in Step 5 "After backwashing, the sand is loose and needs to be reset." I was told after backwashing and rinsing to wait a 1/2 hour before running the pump in Filter mode. This is to allow the sand to settle evenly. Is this true?

I saw in an earlier post that sand should be replaced every 5-7 years. Is that true also for ZeoSand that I use in my filter?


InyoPools Product Specialist  Posted: 6/21/2013 

hodges - You can expect to lose pressure in backwash. The backwash setting has a shorter pipe path and, therefore, less resistance. As long as you have a strong flow coming out the waste line, you should be OK.

 Posted: 6/19/2013 

filters fine but looses pressure when i backwash. what is wrong? how high should pressure be when backwashing?

InyoPools Product Specialist  Posted: 6/9/2013 

Ginny - We have written several How To Guides that may help you. See "How a Multiport Valve Operates" under "Pool Filters" and "How To Set Up In Ground Pool Equipment - Part 1 - Circulation" under "In Ground Pools".

 Posted: 6/8/2013 

HI I have an idoor pool that we are having a few problems with our pump loosing its prime. we have tried a new pump that we loaned and this did the same. the pool level is fine. taps are fully opened.could the sand filter or anything on the pressure side have any thing to do with this or must it be on the suction side.there is no check valve fitted on the suction side so i was wondering if it was building up pressure. could this turn into back pressure on the suction side and empty the pump ?

 Posted: 6/6/2013 

I just got a job at a resort cleaning the pools.
We use the Filter/Backwash/Rinse/Filter procedure.
I am confused with how his works in regards to when i need to
turn off the filter button on my machine, and especially when i turn off certain pipes (like the dock side filter/lake side filter and the 1/2 one) i have the other concept down generally


 Posted: 5/28/2013 

inyopools - I think you just solved my problem. I just read your posts regarding high pressure and I think I may have a blockage. We just opened and cleaned the pool. We did NOT use WASTE function to vaccuum the pool with large debris and I believe it is clogged. For the past few weeks the gauge will not drop down below 10 psi, no matter how many times we BACKWASH and RINSE. So just wanted to say thanks for posting. - NEWBIE

InyoPools Product Specialist  Posted: 5/26/2013 

Frappus - Check to see if your water pressure drops significantly when you run in recirculate mode - bypassing the filter. If it doesn't, you may have a bad pressure gauge that needs to be replaced. If your water pressure drops when you bypass the filter, you may have a blockage in your filter system. If you just opened up your pool and ran very dirty water through your filter instead of out the waste line, you may have a lot of debris yet in your sand or you may have clogged the lateral pipes at the bottom of the vertical pipe in the filter tank. See our guide on "How To Change Sand In a Sand Filter" for more information on checking the laterals.

 Posted: 5/25/2013 

I have done multiple backwashes on my salt water pool and the filter gauge is still at 30 psi showing dirty. Can you tell me what I need to do now? The pool and filter is less than a year old.

InyoPools Product Specialist  Posted: 5/2/2013 

llsunshine32 - This sequence is correct if your filter is due to be backwashed. When you are using the waste port to vacuum debris out of your pool, you are bypassing the sand in the filter, which is correct. No debris is going into the sand during this cycle. So unless you haven't purged your filter for a while, you do not have to go through the backwash and rinse cycles. You can go directly to Filter from Waste.

 Posted: 5/2/2013 

I have a multiport, top mounted sand filter and my question is in what order do I need to go when vacuuming my pool?

I vacuumed my pool for the first time yesterday and this is what I did:
Turned pump off (of course)
Turned valve from filter to waste, hooked hose and everything up and turned it on and vacuumed until all debris was gone.
Turned pump off and moved valve to backwash, ran it a few minutes
then turned it to rinse, ran it a few minutes
then back to filter
(turning the pump off/on appropriately


InyoPools Product Specialist  Posted: 4/15/2013 

Wade - Sounds like the spider gasket in the multiport valve is damaged. This gasket provides seal that controls where water goes when you turn the valve handle. If the pump is not shut off when you move the valve handle, you can blow this gasket. See our guide on How a Multiport Valve Operates II for more information. If you have to look at or replace the spider valve, see our guide on How to Replace a Spider Gasket on a Multiport Valve.

 Posted: 4/15/2013 

I just bought this model pump and filter, and am having a problem with water constantly coming out of the waste port. It sisn't come with a plug to stop it up.

I beleive I have it set up correctly according to Haywards horrible manual.

Any suggestions?



InyoPools Product Specialist  Posted: 3/8/2013 

jonnytyler - If your pump's strainer basket isn't filling up, you have a water suction problem on the incoming side of your pump. For a list of possible problems and solutions, see our guide on "How To Determine Why a Pool Pump Won't Prime".

 Posted: 3/7/2013 

I was wondering? After I back washed my pool
Yesterday I wasn't able to get it to filter. Well at least the water isn't filling up the Cather before the pump. What am I doing wrong


InyoPools Product Specialist  Posted: 1/20/2013 

Rinse cycle - Leave it on the Rinse cycle until the water shows clear in the sight glass. You are cleaning the sand from the other direction.

Anonymous  Posted: 1/18/2013 

When I backwash my Hayward sand filter the waste water and the water in the check valve was clear. Then when I turned it to rince, the water was very dirty. Should I leave it on rince until the wter is clear or just run it for a minute ?

InyoPools Product Specialist  Posted: 1/14/2013 

Bambi - I sounds like you may have blown the spider gasket in the multiport valve. To repair this problem see our guide on "How To Replace a Pool Multiport Valve Spider Gasket".

 Posted: 1/13/2013 

new pool owner here.... We tried to backwash our pool (Hayward) model, but did not turn of the pump when we switched the mode. Now water won't stop coming out of the backwash hose. Did we break it?

InyoPools Product Specialist  Posted: 12/30/2012 

Lenny - If you had a really dirty pool and used your filter to clean it, you may have to backwash your filter a couple of more times. If you haven't changed your sand for 5 years, you might need to replace your sand. For possible solutions for cloudy water look at our Pool Chemical Guide under How To Guides.

 Posted: 12/29/2012 

After I backwash the pool the gauge isn't going back down to blue on gauge is still sitting on two hundred and pool is cloudy what could be the problem


InyoPools Product Specialist  Posted: 12/3/2012 

Mystery - Generally when people backwash their filter, they attach a long hose to the waste port to drain the water away from their pump and the area around it. It sounds like your neighbor needs a longer hose to keep the water from draining into your area.

 Posted: 11/29/2012 

My neighbour has an inground pool and each time they backflush I have a large amount of very soggy ground, you can see the wave like action in the soil where it has come from and always has sand on top. However, they state there are no leaks near their pumps or property, can you please give any information? Thanks.

InyoPools Product Specialist  Posted: 10/18/2012 

Print out - We are trying to correct his problem. Until then try copying the entire procedure to Word and printing it out from there.

Anonymous  Posted: 10/17/2012 

The full proceedure for Backwashing does not print

InyoPools Product Specialist  Posted: 10/4/2012 

backwash leaks - Check your spider gasket. Also check the multiport valve spring. If it is weak or broken, it will not put enough pressure on valve to close the gasket.

Anonymous  Posted: 10/1/2012 

when i switch to backwash i hear pressure relieving and when i turn on pump to backwash it leaks from backwash line and around top of filter

InyoPools Product Specialist  Posted: 9/4/2012 

Tee - Sounds like you have a clog somewhere in your piping. Here are some common problems that lead to low flow: clogged skimmer box, clogged strainer box, clogged impeller, dirty filter, some suction side valves closed off. See our how to guides for correcting many of these problems. If you have a clog in one of your underground pipes, you may have to have a professional look at it.

 Posted: 9/2/2012 

my pool is green so I know I need to backwash but when I turn the pumps on I can hear them , but there are no bubbles coming out in the pool. What could be wrong

Anonymous  Posted: 8/10/2012 

Thanks - I discoverd the problem today. The pump line was plumbed into the return and the return was plumbed into the pump line. Now that it's correct we discovered that the "fingers" in the bottom of the filter are bad and blowing sand in the pool at a stead rate. Frustrating. I only pray that it hasn't damaged my salt system too. My pool builder needs new glasses.

InyoPools Product Specialist  Posted: 8/10/2012 

no water moving - There have been cases where a filter handle was installed 180 degrees off. Try positioning the valve handle 180 degrees opposite "backwash" and see if it backwashes. If not, I would look at the sand.