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.

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Video

Step by Step

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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

Comments

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(161 to 200 of 310)

InyoPools Product Specialist  Posted: 8/4/2015 

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.
 Reply

 Posted: 8/3/2015 

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 ?
 Reply

InyoPools Product Specialist  Posted: 7/29/2015 

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.
 Reply

 Posted: 7/29/2015 

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?

 Reply

InyoPools Product Specialist  Posted: 7/20/2015 

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.
 Reply

 Posted: 7/19/2015 

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?
 Reply

InyoPools Product Specialist  Posted: 7/17/2015 

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".
 Reply

 Posted: 7/17/2015 

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

InyoPools Product Specialist  Posted: 7/8/2015 

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

Anonymous  Posted: 7/8/2015 

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?
 Reply

InyoPools Product Specialist  Posted: 6/27/2015 

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

 Posted: 6/26/2015 

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.
 Reply

InyoPools Product Specialist  Posted: 6/9/2015 

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.
 Reply

 Posted: 6/8/2015 

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.
 Reply

InyoPools Product Specialist  Posted: 6/4/2015 

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.
 Reply

InyoPools Product Specialist  Posted: 6/4/2015 

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".
 Reply

 Posted: 6/3/2015 

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

 Posted: 6/2/2015 

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?
 Reply

InyoPools Product Specialist  Posted: 5/31/2015 

jen - 14 psi is good. You usually don't have to clean a filter until it reaches 20-30 psi. This is more likely a pump motor issue. I assume this pool was operational last year and shut down during the winter season. When you say "the whole thing completely shuts off", it sounds like the motor stopped. If so, your may have a voltage problem. If your voltage is too low, the motor will heat up and stop. Check that the wire connections are tight at the motor terminals. Check the line from the pump to the circuit breaker to make sure it was not damaged. Check that you are getting the correct voltage out of the circuit box and into the motor. Should be 115 or 230 depending on your motor configuration. If you have a switch between the circuit breaker and the pump, check its connections.
 Reply

 Posted: 5/31/2015 

Just opening my in ground pool. Have sand filter. When on filter it runs for about 5 mins or so then whole thing complete shuts off. Could pressure be to high.? It's at 14 psi.
 Reply

InyoPools Product Specialist  Posted: 5/18/2015 

Clueless - Not sure what you are referring to when you say "valves". If they are diverter valves that are used to turn off/on parts of the pool, I would say to leave them open while the multiport valve is in backwash mode.
 Reply

 Posted: 5/17/2015 

Sorry of this sounds stupid, but I really don't know what I am doing. This information is great, but I can't get my head around when to open and close the valves to the pool? Should I have both valves open before I star this process and leave them open throughout?

Thanks

 Reply

InyoPools Product Specialist  Posted: 4/26/2015 

Justin J - If you have to backwash that frequently, you are probably way past the time to replace the filter's sand. I would do that first. See our guides on "How To Change Sand In a Sand Filter" or "How To Replace the Sand in a Pentair Triton 2 Side Valve Sand Filter" for further instructions. Then check the spider gasket in your filter Multiport Valve (MPV) to see if it is damaged and is possibly leaking between ports. See our guide on "How to Replace a Spider Gasket on a Multiport Valve".
 Reply

 Posted: 4/26/2015 

I have a couple questions. Why wont my filter backwash unless I run the rinse cycle first. If I go from filter to backwash and turn it back on nothing happens, but if I go from filter, to rinse, and then to backwash its backwashes just fine. Also it seems I have to backwash frequently, like every couple days. THe jets in the pool get weak, suction is weak and the psi is up. SO i backwash and I'm good for another couple days. IS it time to replace the sand and/or filter completely? I recently bought this house so I have no idea how old the equipment is.
 Reply

 Posted: 4/26/2015 

Im trying to open the pool for the year, and the filter is cycling through power. It'll run normally for a few seconds, then have a burst of power for a few, then back and forth? I tried back washing, but I was worried something was really wrong, so I turned it off. The pool is an absolute mess, and I'm not sure if that has something to do with it. Thanks! I have a video of it would help.
 Reply

InyoPools Product Specialist  Posted: 4/10/2015 

Dawn - I also don't understand why your pool continues to fill with water. Your pool is a self-contained system. The extra water has to come from somewhere outside the system like rain or runoff into the pool. Do you have a sprinkler system that is spraying water into the pool?
 Reply

 Posted: 4/9/2015 

My pool continues to fill with water. When I backwash it is barely backwashing. Then when I rinse the gauge rises back up. Pool is now cloudy but mostly concerned why the water level continues to rise.
 Reply

InyoPools Product Specialist  Posted: 4/8/2015 

Michelle - You only have to backwash a sand filter when the sand is clogged with decontaminates. You will know this when the pressure gauge on your filter creeps up to 10-15 psi above its normal operational range and your spa starts to look cloudy. With little use, I would doubt that you would need to backwash more than 1 or 2 times a month. Depends on how much outside debris is getting into your spa.
 Reply

 Posted: 4/7/2015 

HI There: We have a spa with a sandfilter at work. Is it necesary to backwash the pool on a weekly basis if no one has been in the spa during that period?
 Reply

InyoPools Product Specialist  Posted: 9/5/2014 

BT - See our guide on "How To Go From Cloudy To A Crystal Clear Pool". Also you might want to try a clarifier. This one has good reviews: "Concentrated Clarifier 1 Qt". The sand “puddles” may fine sand getting through the filter, a damaged spider gasket or a broken lateral.
 Reply

 Posted: 9/2/2014 

Have a new Hayward sand filter and pump. After back washing and rinsing (turning the pump off in between each step), the water going back into the pool doesn't look clean. The pool is clear but has a very slight cloudiness to it. I've shocked and kept up with chlorine tabs in the skimmer, and have vacuumed (there are a few small "puddles" of what looks like sand on the bottom after every few days). Any thoughts?
 Reply

InyoPools Product Specialist  Posted: 8/12/2014 

green pool - I would guess the water coming out of the waste port just looks clear because you're not seeing a large volume of it. Try collecting it in a large white bucket to see if it has a green tinge to it. See our guide on "How to Clean a Green Swimming Pool (Algae)" for detailed instructions on clearing your algae. Make sure your chemicals are balanced before you shock and put algaecide in. And you may have to do this process a couple of times.
 Reply

Anonymous  Posted: 8/11/2014 

My pool is green and after treating with algacide, the water coming out in backwash mode is clear. What could the problem be.
 Reply

InyoPools Product Specialist  Posted: 8/11/2014 

Relabstract - Sounds like a damaged gasket. Check your spider gasket on your multiport valve. See our guide on "How to Replace a Spider Gasket on a Multiport Valve" for more information. Remember to shut off the pump every time you change the valve setting to prevent damaging the gasket.
 Reply

InyoPools Product Specialist  Posted: 8/11/2014 

Fuz - Because your pool equipment is above your pool's surface, the water in you pump and filter will tend to drop back into the pool through the suction lines. If your pool equipment is higher than normal, more water will flow back into the pool. You might consider putting in a check valve between the pump and pool to stop this back flow when you shut the pump is off. The initial bubbles coming out of the returns during priming is natural. My guess on the dirty water is it's coming from the filter. Sounds like your filter is draining too when you shut the pump off and when you turn it back on and refill the filter, the action may be dislodging some of the dirt in the filter - somewhat like a partial backwash only the dirt is going out the return ports rather than the waste line.
 Reply

 Posted: 8/10/2014 

When I set back to Filter (after Backwash & Rinse), blows sand back in Pool??
 Reply

 Posted: 8/10/2014 

Hi inyopools, I have a sand filter (not sure what make but is has a plastic casing on top so you can see the water going through. The water seems clear to me but when I turn off the pump, the water seems to drain out over about 5 minutes. Then if I restart it after about an hour or more, it takes about 90 seconds to find its prime, and when it does a lot brown water come out of the return jets followed by some large air bubbles for a minute or so? Any ideas what is wrong as besides this the pool seems fine but I'm having to run the pump 24/7.
 Reply

InyoPools Product Specialist  Posted: 7/8/2014 

Ulysses - If you have low flow in all valve settings, it sounds like you have a blockage somewhere in your system. You already checked the pump impeller so that should be good. If you haven't changed your filter sand in 5-7 years, I would do that. Replace the top 6" of sand first to see if that makes a difference. Make sure some of your diverter valves are open - suction side and return side. Try snaking a line through your pipes to see if you have a line blockage. Please send me another comment, when you resolve this issue for feedback. Thanks
 Reply

 Posted: 7/8/2014 

I do not know what the problem is: My pool pump has been working perfectly for the last couple of years. now, it has no suction to vacuum the pool. When i backwash, it spurs the water instead of what it usually did, water pumping steadily. the same occurs when i rinse.
i've already took the pump apart and found no debris around the propeller. the filters are clean. I do not know what to do

 Reply

InyoPools Product Specialist  Posted: 6/19/2014 

Bret - You may have a blown spider gasket in your multiport valve. See our guide on "How to Replace a Spider Gasket on a Multiport Valve" to see how to inspect and replace a spider gasket if required.
 Reply