Use and care for DE filters

Richard320

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Jan 6, 2010
23,932
San Dimas, CA (LA County)
joshearl said:
So I followed the instructions and did pre soak in TSP and have it now soaking in the acid wash. The biggest bucket I could find was a 32 gallon trash can, which left about 4/5 inches of the grids unable to be soaked as the trash can isn't tall enough. Will this still be sufficient?
Turn 'em upside down and get the other end.
 

Scoop

LifeTime Supporter
Jul 13, 2012
181
Dallas, TX
SaintRonin said:
Thanks, Scoop. I bought a forcelosure and it is my first time as a pool owner. After two seasons, I am still learning, and am glad I came on here to look into cleaning them properly as they were holding water for well over 30 seconds. I will go ahead and get the acid soak going. :)

You're welcome :)

As JasonLion mentioned, it's advisable to to the TSP soak first, ahead of the acid soak. I use "Cascade" automatic dishawashing detergent.

I've cleaned my spare Pentair D.E. Grid set a couple of times using the TSP soak, followed by the acid soak, without any problems. I soaked the grids overnight with TSP, did a thorough rinse, then soaked with Muriatic Acid the next night.

As Richard mentioned, you can flip the grids upside down to soak the exposed part of the grids.

I'm fortunate since I have the 36 sq ft grids (about 18" tall) so my 32-gal plastic garbage can works well for the grids.

Just an fyi, based on my experiences with these D.E. Grids:

I ran my 36 sq ft D.E. Filter for years without pulling the grids and had no adverse effects with filtering. Each pool owner will encounter different grid cleaning frequency requirements, based on several things, environment, swimmer frequency, etc.

I cleaned my existing in-service grids with a water hose-down cleanup and they're working without issues.

My guess is that most pool owners would only need to do the chemical cleanup on rare occastions, or, as was my case, to eliminate the grids as a possible D.E. PSI issue (PSI climbing shortly after backwashes).

I find that daily or frequent checks of the PSI reading on the D.E. Filter Tank is useful to gather data points to better understand my pool's filtering operation.

For a long time, I was backwashing once a month, using the typical "rule of thumb" approach, without monitoring the PSI reading. Since last summer, I've been backwashing based on the PSI reading.

I was able to go about 5 months after the swimming season, between backwashes. I did a backwash on 11/03/12 . The next time I needed to backwash was 03/25/13 . That was due to my pump being off for a couple of days due to an unrelated issue.

I have seen the backwashing frequency increase recently, but I think that's due to the season changing here (Dallas, TX) and I've had a lot of debris falling into the pool with some high-wind weather here.
 

SaintRonin

LifeTime Supporter
Aug 15, 2011
17
Houston Texas
I flipped mine over/upside down. It worked great. Just be careful what you do with that acid water! I would think that you would still get significant benefit from just doing the bottoms, but as much work as it is and the cost of acid and all, just flip them over.

Keep in mind that if you did not TSP soak the tops, the acid could potentially jack up those top 4-5 inches since they were not degreased (based on other warnings and input in this thread). As far as I am concerned, that is just another reason to do the whole thing right the first time. :). Good luck!
 

harleysilo

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Mar 1, 2012
1,939
North Georgia
I was able to get a large enough (45 gallons I think) plastic trash can from Lowe's/Home Depot with a lid such that my entire assembly can fit, it actually floated so i had to weight it down. This is the only thing that trash can will be used for, but it made it really easy to do. Anybody reading this in the future preparing for their first filter cleaning I highly recommend a large enough container.
 

Scoop

LifeTime Supporter
Jul 13, 2012
181
Dallas, TX
harleysilo said:
I was able to get a large enough (45 gallons I think) plastic trash can from Lowe's/Home Depot with a lid such that my entire assembly can fit, it actually floated so i had to weight it down. This is the only thing that trash can will be used for, but it made it really easy to do. Anybody reading this in the future preparing for their first filter cleaning I highly recommend a large enough container.

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I also had the "floating' issue with my grids. I flipped them upside down about halfway thru the soaking time.

I also have a couple of those trash cans that are dedicated to D.E. Grid cleanup use. I store the spare D.E. Grid Assembly inside one of the trash cans.
 

Raiken3712

Well-known member
Mar 18, 2012
71
Lewisville, Texas
If I understand everything correctly after backwashing if the filter pressure is higher than the normal clean pressure than it needs a manual cleaning of the grids. I also read that it can damage the grids if you run without any D.E. How do you tell if there is D.E. or not? Can you tell without opening the filter or is that the only way? We've backwashed about four times and the pressure is now higher than the start pressure of ~10 psi. Its around 15 now though I can't remember what the exact number was. Its enough to make me think it needs a cleaning though.

I guess I'll see if it has D.E. in it when we open it. The pool guy that put it in said to do a full minute backwash, return it to filter position and than do another full minute. We haven't been doing a full minute because it seems clear long before the minute. Is the one minute twice advice good? Also he said to put 9 pounds after backwashing....the filter manual says a full charge is 6 pounds. If he put 9 pounds on the first charge did he add too much?

I'm not sure how much he put in the first time, but I think it was the 9 pounds he told us to put in after backwashing for 1 minute 2 times.

http://www.pentairpool.com/pdfs/FNSPlusOM.pdf

He said we should take out the grids and manually clean once a month. I'm surprised after one day we are already getting to that stage....I guess we did have a bunch of dead algae. I suppose it shouldn't be necessary for a longer time as long as we manage the pools chemistry better. We bought a new filter after they came out to clean our Cartridge filter which wasn't working. They basically said the elements were all bad and it would be better to get a new filter than replace as the filter was a really old one.

Also with the manual hosing should we use pressure at all? Are there good attachments that help to clean the grids..or do you just turn the water on high and let it flow over them.
We ended up getting the D.E. Filter in the sig. Anyone have an opinion on D.E. alternatives as far as cost? I saw a review on Leslie's site that seemed to indicate if you used less of the Cellulose it was cost effective versus D.E. but if you used the standard amount it was quite a bit more expensive.
 

jblizzle

Mod Squad
TFP Expert
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May 19, 2010
43,238
Tucson, AZ
You know there is DE in the filter because you have to ADD IT after every time you backwash. If you have not been adding DE after every backwash, then you likely need to open it up and clean things up.

You should backwash as long and as many times as is required so that the water stays clear.

I am not sure why he added so much, I would stick with the Pentair recommendation of 6 lbs for a full charge (interesting that it is less than the same sized Hayward at 7.5 lbs) ... and then after backwash add only ~4.8 lbs.

I just use a regular hose spray nozzle as high as it goes (not a pressure washer). I spray them "up-side down" so the water can flow out the grids faster
 

Raiken3712

Well-known member
Mar 18, 2012
71
Lewisville, Texas
jblizzle said:
You know there is DE in the filter because you have to ADD IT after every time you backwash. If you have not been adding DE after every backwash, then you likely need to open it up and clean things up.

You should backwash as long and as many times as is required so that the water stays clear.

I am not sure why he added so much, I would stick with the Pentair recommendation of 6 lbs for a full charge (interesting that it is less than the same sized Hayward at 7.5 lbs) ... and then after backwash add only ~4.8 lbs.

I just use a regular hose spray nozzle as high as it goes (not a pressure washer). I spray them "up-side down" so the water can flow out the grids faster

I'm aware I'm supposed to add some back. I'll make sure to do so after we clean it. Just wanted to make sure to get the proper amount to add. Since we are going to need to open it up and clean it I guess we are going to be started from 0 and so will add the 6 pounds. I'll make sure to send him a link to this thread so he has the details on proper cleaning procedure since I'll be at work.

We didn't add any after backwashing because we don't have any replacement. Since hes opening it we'll make sure to clean it all off and start with fresh. I'm surprised it got to the manual cleaning so fast. Guess that means we had a bunch of stuff in the pool. They mentioned paint residue so I guess thats part of it. They said the D.E. should be able to handle it though. Perhaps it'll shorten the filter cycle some though. He'll by some replacement when he takes me to work I guess.
 

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Raiken3712

Well-known member
Mar 18, 2012
71
Lewisville, Texas
My brother would rather just add D.E. and backwash again until the pool clears. I think its a better idea to clean it first since the starting pressure is up to 15 from 10. The pressure being higher means there is stuff inside that needs to be cleaned and it won't filter as well without a manually cleaning right?

I guess it'll still filter that way, but I'm thinking it would be better to do a manual cleaning before continuing to filter and backwash.
 

jblizzle

Mod Squad
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May 19, 2010
43,238
Tucson, AZ
If it was run without enough DE for any time (I am not clear if this happened or not), then particles could be clogging up the grids and just backwashing will not clean them out. You will need to take the assembly apart and spray each one down. Then if there is any doubt about the history, you could also do the TSP soak and acid soak and know you are starting fresh.
 

harleysilo

TFP Expert
LifeTime Supporter
Mar 1, 2012
1,939
North Georgia
So let me get this straight....

You filter was started with too much DE, wash back-washed multiple times with no DE replacement, and now is in need of back-washing. Is that right?

I could take off my filter cover in 2 mins., and rinse my filter in about 15 with a hose, it might not be much different for you or your brother, i think it would be worth it to know that it is functioning properly. Sounds like we have no idea how much DE is in it at the moment.
 

Raiken3712

Well-known member
Mar 18, 2012
71
Lewisville, Texas
jblizzle said:
If it was run without enough DE for any time (I am not clear if this happened or not), then particles could be clogging up the grids and just backwashing will not clean them out. You will need to take the assembly apart and spray each one down. Then if there is any doubt about the history, you could also do the TSP soak and acid soak and know you are starting fresh.

I'm clear on my plan of action than thanks for the clarification.
 

SHADEZ

Well-known member
Jul 10, 2011
95
Is there a con to using sodium bi-sulfate (dry acid ) to acid wash a DE filter grid as opposed to muriatic acid?
Besides maybe having a wait a little for the dilution and possibly soaking a little longer?

Do we just dump the left over dirty water cleaner and acid mix on the ground away from the pool?
Is there a better safer way?
 

Scoop

LifeTime Supporter
Jul 13, 2012
181
Dallas, TX
SHADEZ said:
Is there a con to using sodium bi-sulfate (dry acid ) to acid wash a DE filter grid as opposed to muriatic acid?
Besides maybe having a wait a little for the dilution and possibly soaking a little longer?

Do we just dump the left over dirty water cleaner and acid mix on the ground away from the pool?
Is there a better safer way?

I haven't tried the sodium bi-sulfate idea but with regards to your other question about Muriatic Acid/water disposal, here's what I did the last time that I soaked my Grids in that solution.

I used Baking Soda to neutralize the Muriatic Acid/water mix and then poured it out in my back yard in a corner of the yard while also running a hose to dilute it as it was emptied into the corner of my yard.

The only part that's a little costly, is that it requires a substantial amount of Baking Soda to fully neutralize the mix that I was using, which was a 10:1 Acid/water mix.

I looked up some info on Hydrochloric acid (Muriatic Acid) and how to neutralize it. That's where I found the info about using Baking Soda as a neutralizing agent.

Hydrochloric Acid neutralization using Baking Soda:

Amount of Hydrochloric Acid spilled (Amount of Baking Soda needed in pounds)

1 gallon (5.5)
2 gallons (11.0)

I verified the neutralization with Ph test strips.

This is just my take on my experiences with my D.E. Filter Grid maintenance, but I'm inclined to believe that it's rarely necessary to clean the Grids with Muriatic Acid. I'm sure it'll depend on one's individual pool cleanliness and amount of calcium, etc, in the water but the last couple of times that I've pulled my Grids, I've just done the hose-down cleaning and re-assemble with good results.

I also ran my D.E. Filter for several years without any maintenance, excepting periodic Backwashes, and I didn't have any Grid/circulation/filtering issues. However, that approach wasn't too wise (not pulling the Grids annually or other chosen frequency).

I'm coming up on 7 months since my last Grid pull/cleaning so I'm not sure about pulling the filter this year as yet.
 

FamilyGuy

LifeTime Supporter
Jun 30, 2013
415
SpringHill FL
When you say add "some" tsp. about what concentration should i be looking to acheive? For example do i mix a whole box, half a box, or some other amount when degreaseing the grids for their acid bath.
 

jblizzle

Mod Squad
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May 19, 2010
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Tucson, AZ
FamilyGuy said:
When you say add "some" tsp. about what concentration should i be looking to acheive? For example do i mix a whole box, half a box, or some other amount when degreaseing the grids for their acid bath.

Good point ... I just scanned and nowhere is it mentioned how much TSP or detergent to use.
 

Scoop

LifeTime Supporter
Jul 13, 2012
181
Dallas, TX
FamilyGuy said:
When you say add "some" tsp. about what concentration should i be looking to acheive? For example do i mix a whole box, half a box, or some other amount when degreaseing the grids for their acid bath.

jblizzle said:
FamilyGuy said:
When you say add "some" tsp. about what concentration should i be looking to acheive? For example do i mix a whole box, half a box, or some other amount when degreaseing the grids for their acid bath.

Good point ... I just scanned and nowhere is it mentioned how much TSP or detergent to use.

I recall when I was searching last summer for this info and the only procedure that I found was one was this one:

Try soaking them in automatic dishwasher powder such as Cascade or Electrosol. Use one cup per every 5 gallons of water and soak for at least one hour to overnight, use a soft brush to carefully scrub the grids if anything is sticking to them and then hose them off. If they are showing calcium or metal stains after that then soak them in a dilute muriatic acid solution for about 20-30 minutes or until the bubbling stops. Use 1 cup acid to every 5 gallons of water.

I used this procedure several times last summer with both sets of my D.E. Filter Grids and it's worked good, no adverse effects noticed.
 

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