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 184)

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User: Inyopools

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.

User: 

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.

User: Inyopools

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".

User: Jessica

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?

User: Inyopools

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".

User: nccowboy66

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?

User: Inyopools

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".

User: Dani

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!

User: Inyopools

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".

User: Dee

Hi y'all,

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

Thanks!
Dee

User: Inyopools

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.

User: jlmrww

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.

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?

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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.


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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.