How To Backwash a Pool Sand Filter

WRITTEN BY:  Inyo Pools

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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.

Video

Step by Step

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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

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(1 to 40 of 206)

Inyopools  Posted: 09/13/2016 21:59 PM  Inyo Product Specialist

valbo - It sounds like you problem is the pump not priming. See our guide on "How To Prime a Pool Pump". Also check to see if your pump's impeller is clogged. See our guide on "How To Clean Out a Pool Pump Impeller".


valbo  Posted: 09/10/2016 17:51 PM 

All valves are open and my hose is ready to receive dirty water. I've set to backwash and turned on the pump. No water leaving the filter, pool, anything. Any advise on why and what to do now?


Mister Dave  Posted: 08/10/2016 21:28 PM 

My filter pressure runs 14 psi after a good flush. One return jet to above ground 24' pool. I feel good pressure from the jet about three feet into the pool. When this declines significantly to say a foot from the jet, I figure I am overdue for a backflush. The pressure rise is only about 3. Hayward 100 pound sand, 2-horse pump.


Inyopools  Posted: 07/28/2016 11:34 AM  Inyo Product Specialist

TMK - It sounds like 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 prevent damage to the spider gasket, make sure the pump is turned off before changing MPV settings.


TMK  Posted: 07/26/2016 19:06 PM 

When I backwash, and this just started two back washes ago, dirty water also gets sent back into the pool through the jets?!? Anybody know what is wrong?


Inyopools  Posted: 07/19/2016 18:55 PM  Inyo Product Specialist

Judi WV - No, there is no advantage to letting your sand filter sit before backwashing and rinsing. The debris is embedded in the sand. Backwashing lifts the sand up into the top of the tank to separate it and loosen up the debris to be purged out the waste line. Rinsing pushes the sand back down to repack it and remove any loose debris left in backwashing.


Judi WV  Posted: 07/17/2016 16:42 PM 

I am new to using a sand filter. Had DE filter in the past. My question is, is it best to let the filter sit not running for any length of time before backwashing and rinsing in order for debris to settle? It is a Hayward sand filer.


Inyopools  Posted: 07/12/2016 19:39 PM  Inyo Product Specialist

kathy - The sight glass in on the Waste port and only shows flow when the water is going out the Waste post. Check your pump impeller to make sure it is not clogged and restricting good flow. Check your chemical balance and in particular the pH valve. Get your pH value down to 7.4. High pH can contribute to a cloudy pool. If none of these suggestions work, backwash your filter, shock your pool, and run your pump continuously until the pool is clear. Backwash your pool 2 times a day while the pool is clearing.


Inyopools  Posted: 07/11/2016 9:16 AM  Inyo Product Specialist

Jgibson - If you haven't replaced the sand in your filter for a while, you might try that. Or sometimes the pressure gauge itself goes bad and needs to be replaced.


kathy  Posted: 07/10/2016 16:30 PM 

my pool has been cloudy all season. Just changed 150 lbs of sand in my Hayward Sand filter. Still cloudy. 2 days later, I just noticed that the water is not moving freely around like it normally does in the sight glass while the filter is running. The water is just sitting, stagnant in the sight glass. Any idea why the water in the sight glass is not moving around like it usually does while the filter is running?


Inyopools  Posted: 07/08/2016 14:25 PM  Inyo Product Specialist

Leaking backwash - It sounds like the spider gasket in your Multiport Valve may be damaged and is letting water leak into the Waste port. See our guide on "How to Replace a Spider Gasket on a Multiport Valve" to locate and possibly replace this gasket.


Jgibson  Posted: 07/08/2016 11:33 AM 

I have a 15x48 round above ground pool. The pressure gauge on my Proline 94440 Sand Filter hovers around 29 PSI. I have back washed it a few times since opening the pool two weeks ago. However, the PSI has not dropped. Do I need to replace anything?


Anonymous  Posted: 07/05/2016 20:48 PM 

After back washing I placed the valve back in filter mode as always. This time the system continued to slowly fill the hose with water as if I were still back washing. The system continues to remove water from the pool. What should I do to stop this from happening. I am refilling the pool with water. Help


Inyopools  Posted: 07/02/2016 11:21 AM  Inyo Product Specialist

ksmart - In BACKWASH mode the water should come out the Waste port. See our guide on "How a Multiport Valve Operates".


ksmart  Posted: 07/01/2016 19:48 PM 

ok, where is the water supposed to come out when I BACKWASH my sand filter?


Inyopools  Posted: 07/01/2016 13:05 PM  Inyo Product Specialist

Sanmann7 - Make sure your pool chemicals are balanced. Have your pool store check your phosphates level. That can cause cloudiness. Also, backwash and rinse the sand 2-3 more times to clean out the filter.


Sanmann7  Posted: 06/30/2016 12:07 PM 

I have cloudy water after super shocking the green out. Have ran pool pump constantly and clarifier twice but still cloudy ?


Inyopools  Posted: 06/28/2016 12:19 PM  Inyo Product Specialist

john - I think you are referring to the drain plug at the bottom of your sand filter and not sand pump. Check the parts list for you filter to see if you are missing an O-ring or gasket. Click "Replacement Parts"; find your manf and filter model; and look at the diagram of parts around your drain plug.If your model has no O-ring or gasket, try wrapping 4-5 layers of plumber's tape around the threads that the plug attaches to.


john  Posted: 06/27/2016 14:49 PM 

at the bottom back of the sand pump their is a drain plug threaded I have thightened it as far as it will go and their is a leak at the top of the drain plug, no cracks that I can see, I have the right size threaded cap that goes with the pump not sure why its leaking??


Inyopools  Posted: 06/26/2016 13:09 PM  Inyo Product Specialist

jacki - It sounds like the spider gasket in your multiport valve is damaged and is letting waste water into the return port when you backwash. See our guide on "How to Replace a Spider Gasket on a Multiport Valve" to locate and possibly replace this gasket.


jacki  Posted: 06/24/2016 16:48 PM 

How do i backwash without getting the dirty water into my pool after the initial adding of new sand.


Jacki  Posted: 06/24/2016 16:37 PM 

I changed out the sand in my pool this year but when I turn the pump on to Backwash the dirty water from the tank goes into the pool. Do I need to close the inlet valve to the pool before backwashing. I dont want this dirty water in my pool.


Inyopools  Posted: 06/22/2016 10:34 AM  Inyo Product Specialist

closed filter overnight - Your filter is probably alright. I'd check the spider gasket in the multiport valve. See our guide on "How to Replace a Spider Gasket on a Multiport Valve". And your pump may have taken the hit. With no water flow, it had nothing to cool it. Watch for leaks around the pump gaskets and replace them if required.


Anonymous  Posted: 06/21/2016 23:17 PM 

I accidentally left my sand filter in backwash position overnight with ball valve closed on the waste line. Didn't realized until next morning when I realized the pump didn't sound normal. Pump was hot when I corrected the setting back to filter. Could I have damaged the sand filter. Pool water has been cloudy four days now.


Inyopools  Posted: 06/20/2016 14:47 PM  Inyo Product Specialist

Jessica - Do you have any water flow at all? Try putting you multiport valve in Recirculate mode which bypasses the filter. I no or little water flows, your problem isn't the filter. You have a block somewhere in your system. One of the most common system blocks is in your motor's impeller. See our guide on "How To Clean Out a Pool Pump Impeller".


Jessica  Posted: 06/18/2016 14:34 PM 

In my sight glass there's greens stuff in there what does that mean? I need help everything about my filter isn't working the filter itself won't do anything and neither will the backwash it just stays still and nothing happens it all started happening after I was vacuuming the pool and dirt started coming out of the jet holes so i stopped and tried to backwash it but nothing happened water wouldn't come out of the hose so I turned back to filter and nothing happened what do I do?


Inyopools  Posted: 06/17/2016 15:57 PM  Inyo Product Specialist

nccowboy66 - Depends on the size of your pool. If your recommended pump was 1.5 HP, 2HP is probably more than you need. But if you are maintaining 10-11 psi on your filter gauge, you are probably all right. It might also turn out that your 2.0 HP pump is close to your 1.5 HP pump. See our guided on "How To Understand True Pump Horsepower - Up Rated vs Full Rated".


nccowboy66  Posted: 06/15/2016 9:10 AM 

I have a Hayward S-210T and have had to replace the pump and skimmer housing with a 2Hp pump the recommended pump size is 1.5Hp have I made a mistake with the 2Hp pump My pressure stays around 10 to 11 psi and I backwash and rinse every time I vacuum or after the pump runs for a week or longer?


Inyopools  Posted: 06/07/2016 10:54 AM  Inyo Product Specialist

Dani - Check that nothing is stuck in the throat of the cleaner. Then check that the pump's impeller is not clogged. See our guide on "How To Clean Out a Pool Pump Impeller".


Dani  Posted: 06/05/2016 19:12 PM 

I have a 13x27 above ground super splash pool, started up this year, everything worked great. then a week ago the vacuum didn't have enough suction to run the shark. Back flushed, rinsed, no help....any suggestions would be great!


Inyopools  Posted: 06/02/2016 17:08 PM  Inyo Product Specialist

Dee - You might have a damaged spider gasket in your filter's multiport valve, or you may have a cracked standpipe or lateral or lateral hub in the sand filter. See our guides on "How to Replace a Spider Gasket on a Multiport Valve" and "How To Replace a Lateral in a Pool Sand Filter".


Dee  Posted: 06/01/2016 17:28 PM 

Hi y'all,

What does it mean when there is sand in the backwash?

Thanks!
Dee


Inyopools  Posted: 05/30/2016 14:01 PM  Inyo Product Specialist

jlmrww - Check for cracks in the standing pipe and hub of your lateral assembly. These could be letting sand into the laterals and clogging them.


jlmrww  Posted: 05/27/2016 15:34 PM 

The filter setting on my pump isn't working - it will backwash and rinse, but nothing when it's on filter. The pump runs but nothing drains.


Inyopools  Posted: 05/23/2016 14:28 PM  Inyo Product Specialist

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".


Inyopools  Posted: 05/23/2016 14:24 PM  Inyo Product Specialist

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."


first time  Posted: 05/22/2016 8:45 AM 

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!


dan  Posted: 05/17/2016 13:39 PM 

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


Inyopools  Posted: 05/17/2016 12:20 PM  Inyo Product Specialist

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.


Dan  Posted: 05/17/2016 7:16 AM 

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????