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How To Backwash a Hayward DE Filter

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A Diatomaceous Earth (DE) Filter cleans your pool water by passing the water through a set of normally 8 grids. Each of these grids is covered with a layer of DE powder. If your pools water is not clear and/or your filter's pressure gauge is reading about 10 psi higher than normal, It's time to backwash your pool filter to strip the current layer of DE power off the grids and replace it with new powder. Although this guide is specific to a Hayward Pro Grid DE Filter, many of its steps are applicable to most DE filters.  Note: About once a year you should take the grids out of your DE Filter and clean them more thoroughly. See our guide on "How To Remove and Clean Hayward DE Filter Grids" for more information.

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Step 1

BUY DE POWDER - You will need about 4-6 pounds of DE Powder to replace the old DE Power that is stripped off of the grids during backwash. Buy this ahead of time so it is available when you need it. The DE powder is available in large bags (like 25#s) which will last for 4-6 separate backwashes.

Please click here to view our D.E. powder and accessories 

Step 2

ROLL OUT WASTE HOSE - Roll out the backwash hose to drain the pool water and old DE Powder away from your pool equipment.

Please click here to view our backwash hose 
Please click here to view our hose clamps 

Step 3

TURN PUMP OFF - If your pump is on, turn it off at the power switch or ideally at the circuit breaker box. You should not change modes of operation on the Multiport Valve with the pump on. You will damage the spider gasket in the Valve.

Step 4

ROTATE MPV HANDLE TO BACKWASH - Rotate the Multiport Valve Handle to the "BACKWASH" position. Be sure to depress the Handle all the way down and hold it down as you rotate it.

Step 5

TURN PUMP ON AND BACKWASH - Turn the Pump back on and backwash for 2-3 minutes to strip the old DE Powder and contaminates off the filter grids. The flow of water during a Backwash cycle is reversed from that of the Filter cycle and dirty water and old DE Powder is washed out the waste line. Note: This process will lower your pool's water level slightly. If it started low, you may have to add water to the pool with a garden hose.

Step 6

MONITOR SIGHT GLASS - As you backwash the filter, you should see the water in the sight glass change from cloudy to clear.

Step 7

TURN PUMP OFF - Turn off power to the pump again to set up for the "RINSE" cycle.

Step 8

ROTATE MPV HANDLE TO RINSE - Push down on the handle while rotating it to the "RINSE" position.

Step 9

TURN PUMP ON AND RINSE - Switch the pump back on for 30 seconds or so to rinse the grids from the normal Filter side of the grids. In this mode, water flow is switch back to flow in the same direction as it would in the Filter mode, except the water and any remaining residue is purged out the waste line.

Step 10

TURN PUMP OFF - Switch the pump off again.

Step 11

REPEAT BACKWASH AND RINSE - If it's been awhile since you backwashed your filter, you may want to repeat the Backwash / Rinse cycle again to get any stubborn DE Powder and contaminates out. Repeat steps #3 through #10. If not, continue to the next step.

Step 12

TURN PUMP OFF - Switch the pump off.

Step 13

ROTATE MPV HANDLE TO FILTER - Push down on the handle completely while rotating it to the "FILTER" position.

Step 14

TURN PUMP ON - Switch the pump back on to add new DE Power.

Step 15

ADD DE POWDER - Go to our guide on "How To Add DE Filter Powder"

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(1 to 12 of 12)

 Posted: 7/3/2019 

Hi, should you only rotate the handle on the MPV in a certain direction? I was taught to only go clockwise, but your video shows the gentleman going counter-clockwise in one of the steps. Can you help clear this up?
 Reply

InyoPools Product Specialist  Posted: 7/3/2019 

Pick which way you want to turn the handle when the valve is installed, then stick with that direction. Whether it is clockwise or counter-clockwise, it does not matter.
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 Posted: 2/13/2019 

At which point will the pressure gauge lower its reading after the backwash cycle or rinse cycle?
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InyoPools Product Specialist  Posted: 2/13/2019 

Hello Eric - The PSI should drop after backwashing the filter. If the PSI remains high after backwashing and rinsing, the sand may need to be replaced.
 Reply

 Posted: 2/19/2019 

The pressure on my Hayward Sand filter reads high ~10 psi according to the owner manual when it reads this way, one should run the back wash procedure and that will lower the pressure. However, this didn't lower the pressure on my system. The Filter was there before I moved in and is about 10 feet below the pool, could the pressure by due to the difference in altitude? making 10 my baseline? or does it mean its time for me to change the sand? I believe the filter had its sand changed about 3 years ago. It is a model S310T2
 Reply

InyoPools Product Specialist  Posted: 2/20/2019 

Hello Eric - 10 PSI wouldn't be considered a high reading. That would be the starting pressure for a lot of pools. You should backwash the filter when it rises 10 PSI above the clean starting pressure. In your case, you'd backwash when the PSI hits 20.
 Reply

InyoPools Product Specialist  Posted: 7/3/2017 

mack - It really depends on how well your DE filter is performing - If your water is becoming cloudy or your pressure won't come down after backwashing, you should take to take the grid assembly out and hose the DE powder out of the grids. If that doesn't solve your problem or you are seeing DE powder in your pool, you should take the grid assembly apart to check each grid for tears or collapsed inner framework. Torn grids should be replaced. Grids should be cleaned individually and possibly soak in a cleaning solution to get embedded oils and chemical out of the fabric.
 Reply

 Posted: 7/2/2017 

How many times can you backwash a DE filter, before you need to take a part the filter and clean it ?
 Reply

Anonymous  Posted: 1/27/2020 

How many times can you backwash a DE filter, before you need to take a part the filter and clean it ?
 Reply

InyoPools Product Specialist  Posted: 2/10/2020 

There is not a prescribed amount of backwashes you can complete between deep cleanings of your DE grids. The need for a deep clean is on a pool by pool basis. Generally, you can get away with doing one deep clean a year, as long as you haven't experienced heavy algae or chemistry issues.
 Reply

Anonymous  Posted: 6/30/2016 

Clear and easy to understand... thank you so much.
 Reply

 Posted: 5/31/2016 

Your site and videos have saved me so much time and money. I have been through 2 lousy pool services then decided to do it my self. I have learned so much from your site about proper pool maintenance I am confident enough to do it my self. If I hire another service I now know enough not to get taken advantage of. I am also very pleased with the robotic sweeper I purchased from you. Thank you!!!
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