Replacing filter grids

iceflow

Well-known member
Jul 25, 2010
147
Folks,
Are there any tips or general 'gotchas' to watch out for when changing out DE filter grids? I have a DE Nautilus and have noticed one grid in particular getting tears going back 12 months or more. I've repaired them with fishing line and blobbed silicone glue over the repairs. That's held up well but it's time to replace some, maybe all the grids. Any tips on the dismantling process would be gratefully received no matter how small.

Thanks
Regards
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,445
San Dimas, CA (LA County)
Wear old clothes.






Be sure to lubricate any O-rings. Any not with petroleum products. Buy a tube of silicon grease at the pool store. You've had it apart to sew it up, right? This should be even easier.
 

iceflow

Well-known member
Jul 25, 2010
147
Thanks.
Actually I never pulled it apart to repair the tears. I was able to see them. Anyway I'll proceed with caution when dismantling it. The reason I posted is I had a pal that pulled one of these apart and said he had a devil of a job fitting it back together. Maybe he just didn't watch what he was doing. Thanks for the info.
Regards
Chris
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
iceflow said:
Thanks.
Actually I never pulled it apart to repair the tears. I was able to see them. Anyway I'll proceed with caution when dismantling it. The reason I posted is I had a pal that pulled one of these apart and said he had a devil of a job fitting it back together. Maybe he just didn't watch what he was doing. Thanks for the info.
Regards
Chris
It might help to take some pictures of the grid/manifold assembly, from all angles, before taking it apart. Also, find the manual online and print it up.

Manual http://www.pentairpool.com/pdfs/FNSOM.pdf

With searching you can get really good prices for a whole set of grids, online. For my old, 36 sq ft, I found a whole set for about $100.

Before disassembling, use a magic marker to mark where the bolt are located on the long rods, top and bottom.

Word of caution, too. When you put each grid into the hole of the manifold work it in slowly and don't "brute force" too much. As you are doing it watch to make sure the fabric around the tube, of the grid, fits into the hole nicely. When you put the long bolts back in you can tighten each bolt and then the other, and then back to the first and so forth. That will see-saw the grids more firmly into the holes of manifold. A very, very, very gentle tap on the manifold top (VERY GENTLE), at several places, with a rubber mallet, helps to get them in too. Do some see-saw tightening, and then do a little tapping. Do that again, etc.

When you have the manifold top and bottom grid holder off inspect them well. Check the nibs that hold the grids in place, top manifold and bottom grid holder. If any are broken it may cause the grids to squish together, when at high pressure, and may allow them to flap around some, putting undue stress on the skeleton of the grids, and lower your filtration efficiency. Broken nibs may also allow more DE to be retained in the filter when backwashing.

I've never done it but there may be something that one can put on the tube to make it slide into the manifold holes more easily. Lets let some experts comment on that.

Before you put the top of filter back on inspect any O-rings you see. Clean and lubricate them, or replace (inexpensive) if needed. Inspect that the manifold screen is present and in good condition. The size of the screen is from about .5" or larger and is located on the top of the main manifold.

Clean well the filter body around where the bit huge O-ring goes, where the top and bottom fit together. Check the O-ring for integrity. Clean it well and lubricate it. I've had one last for 19 years by keeping it clean and lubricated and using non-silicone 303 Space Protectant to revitalize and protect the rubber.

Inspect the clamp bolts and nuts well. This is a good time to replace them if needed and put something like white grease on them. The edit nut not bolt is the most likely thing to break down. Note that the bolts are a special kind that has nibs near the head to keep the bolt from turning when you tighten it down (old style). On new style make sure of the integrety of the spring/bolt/washer assenbly. I misplaced one of the heavy duty washers on my new Pentair filter so used a couple of light duty washers. (I found it later) But the light duty washers, doubled stacked, deformed from the pressure.

During tightening down the clamp, gently tap around the clamp band a few times between tightening the bolts. This helps to seat it properly.

I previously had a stainless steel filter so I didn't have any problems with itchy arm from handling the filter body. Some filter containers can irritate your skin when you grasp around them. Wear long sleeves or spray arms with hair spray to avoid this.

Hope this helps some.

gg=alice
 

ride525

Gold Supporter
Jun 17, 2010
316
Pleasanton, CA
I just replaced my filter grids. Looks like a very similar design to yours, going by the manual geekgranny posted.

Note: there is one small grid, and seven full sized grids in that setup. The small grid goes near where the outlet is in the grid assembly, and it is marked on the uppper manifold.

There is a long bolt with a nut, holding the top manifold, and bottom of the grid assembly together. I found it easier to put the grids in upside down, with the manifold on the deck, then the eight grids, and the putting the plastic grid retainer bottom on last.

It took two of us awhile, wiggling the grids and the plastic grid retainer bottom a bit each, then another, then another, to adjust, and get all eight grids to slip in and fit right, so the nut could be tightened back the way it was.

Jeff
 

iceflow

Well-known member
Jul 25, 2010
147
Folks,
I very much appreciate the replies, especially geekgranny who has aken a fair bit of time to really orientate me to the task. Thanks very much. I find these boards invaluable at times like this. I'm also on a Mazda MPV board and have gained great insight there when I've needed to work on my van. Take care and thanks.
Regards
 

iceflow

Well-known member
Jul 25, 2010
147
I'm getting ready to finally do this job, thanks folks for taking the time to help orientate me to the task.

Regards
 

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