Filter Backwash - How often for DE?

RichTJ99

Gold Supporter
Sep 16, 2016
188
Katonah NY
#1
Hi,

Thanks to you guys i think I am going to save $1500 this year & handle my pool myself. I am starting to get the hang of things, I cleaned my DE filter about a week ago. My pool company opened the pool, cleaned the filter, added DE. A few days later it was still cloudy.

I opened the filter, cleaned it, added more DE & off i went. A day or so later the water was clear.

So my question is how often should i backwash the filter vs open the canister to manually rinse the grids?

How much DE do I add when backwashing? How long do I backwash?

Thanks so much for the help!

Rich
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
10,846
Bedford, TX
#2
Rich,

The TFP standard answer is backwash or clean when the clean pressure increases by 25%...

Personally I never backwash, as I have variable speed pumps and run them at about 1,200 RPM most of the time. I open and clean them twice a year...

This is not something you can do if your water is cloudy due to an algae outbreak..

When I did backwash I added about 80% of the clean DE requirement. You backwash until the sight glass is clear, and I would do that twice..

Thanks,

Jim R.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,328
San Dimas, CA (LA County)
#3
I use cellulose instead of DE and I backwash twice a year. I learned the hard way that once the pressure goes up 25% it's just a matter of days before it's up 50%. seems to be something with the cellulose, like it starts decomposing or something, since it is biodegradable. My backwash valve is integral in the base of the filter, so I backwash for a few seconds until the water out the end of the hose starts clearing. Then I open it up and remove the top manifold to get a little wiggle room and get in there with a jet spray nozzle to blast any sticky stuff off. Since it all drains out the bottom, it just runs out the backwash hose. Reassemble, flush again long enough to clean out the hose, and I'm done. Fifteen or twenty minutes is all.

DE never rinses off completely, and cellulose even less so, in my experience, so opening it up is part of it for me.
 
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RichTJ99

Gold Supporter
Sep 16, 2016
188
Katonah NY
#4
I use cellulose instead of DE and I backwash twice a year. I learned the hard way that once the pressure goes up 25% it's just a matter of days before it's up 50%. seems to be something with the cellulose, like it starts decomposing or something, since it is biodegradable. My backwash valve is integral in the base of the filter, so I backwash for a few seconds until the water out the end of the hose starts clearing. Then I open it up and remove the top manifold to get a little wiggle room and get in there with a jet spray nozzle to blast any sticky stuff off. Since it all drains out the bottom, it just runs out the backwash hose. Reassemble, flush again long enough to clean out the hose, and I'm done. Fifteen or twenty minutes is all.

DE never rinses off completely, and cellulose even less so, in my experience, so opening it up is part of it for me.
So yesterday I saw the pressure was at about 18, I backwashed for 30 seconds, turned it on & the pressure is sitting around 9. I added about 4 pounds of DE into the skimmer - is that pretty much all I need to do? The lower the PSI the less resistance within the pipes?
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,328
San Dimas, CA (LA County)
#5
So yesterday I saw the pressure was at about 18, I backwashed for 30 seconds, turned it on & the pressure is sitting around 9. I added about 4 pounds of DE into the skimmer - is that pretty much all I need to do? The lower the PSI the less resistance within the pipes?
That's it for normal backwashing. After you recharged it, that's your clean pressure. When it rises 25%, it's time again. For a plain backwash, we recommend 80% of the initial fill quantity, since it never washes out 100%. If you open it up and clean it all out, then you use the full amount.

Check out DE Filter Cleaning Tutorial just for the worst-case picture. It's worth it.
 
Aug 4, 2015
10
Anaheim
#7
I notice that after doing a thorough cleaning of my 2 year-old pentair filter grids, including taking it apart and thoroughly spraying down and cleaning every bit of debris from fiberglass housing and parts) it needs a backwash again only after 3 weeks. The pool was used only a couple times and there is no unusual debris going into pool. 15k gallon pool. 60' filter. Put in 12 measured cans on DE. The pressure was great and the pool cleaned effortlessly at the beginning. Now I have to crank up pump to 3000 rpm to get barely anything to move. I will back wash again, but the frequency is getting closer day to day where I have to do it again.

Don't know what the problem is.

The filter grids looked great. Just under two years old anyway.

You guys are the best!
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
10,846
Bedford, TX
#8
my,

The number one reason that filters quickly clog is because they are just doing their job. Most likely you have an algae outbreak and that is what is causing your need to backwash so often..

Please post a complete set of numbers as follows...

FC
CC
pH
TA
CH
CYA

Thanks,

Jim R.
 
Aug 4, 2015
10
Anaheim
#9
The pool does get a green tinge on the walls and clouds pool after scrubbing. Last time I looked at grids they were as green as a shamrock.

I will get those numbers. Many thanks, Jim.
Charles.


my,

The number one reason that filters quickly clog is because they are just doing their job. Most likely you have an algae outbreak and that is what is causing your need to backwash so often..

Please post a complete set of numbers as follows...

FC
CC
pH
TA
CH
CYA

Thanks,

Jim R.
 

pjt

Active member
Jan 7, 2012
38
Hanford, CA
#10
If you keep your chemistry in check, you may not ever need to backwash. I have never backwashed my filter. I just disassemble and clean it every 12-18 months. IMHO, if you're going to go through the hassle and mess of backwashing, you may as well go all the way and disassmeble for a thorough cleaning. Plus, by completely disassembling, you can precisely measure the DE instead of taking a guess at how much to add.