Filter grid failure for a relatively new Pentair DE filter

[PPS222]

Today I had to have a service call after tearing down my system for a routine cleaning and being unable to figure out why I was blowing DE back into the pool when I recoated the grids. After some close inspection with the pool guy we finally saw that ALL but one of my grids and totally blown out at the bottom of the grid. There were no threads left and the bottom of the grid material on all but one of my grids was totally open ... not just a small rip ... but the entire bottom of the grid material was totally open and there was not stitching left at all or evidence of stitching. Pool guy said he had never seen this before.

No, I back-flush pretty regularly and no, I did not have any pressures on the gauge above 20 psi. I maintain my chemistry and its never been out of hand.

I am thinking I got a batch of bad grids all manufactured at the same time. Only the short grid was OK. All of the long ones were blown out. The system was 4 years old. It was an expensive day.

Anybody else experienced grid failure from Pentair grids purchased in the 2014 time frame??

I have had customers with relatively new Pentair filters 48sqft and have seen this happen a few times. I personally think Pentair put out bad grids. I have never seen this happen to older sets of grids or aftermarket sets of grids. I remember because the customers were trying to blame the guy cleaning the filter and I was the guy on one of the occasions it happened. I don't know when they were manufactured or when the distributor had purchased them originally but it's hard to explain to someone that has a pretty new filter system why the grids blew out and why it's not under warranty. So now I'm traumatized from pentair original filters. I'm kidding but I am weary now. I recommended the customers to call Pentair but I don't know if anyone did. If anyone gets any info in regards to this please post. This pic is from 2 days ago when my tech notified me. Craziest thing happened. It was originally 1 grid and it was replaced. When reassembled and tested again there was still blow back! It was taken apart again and 3 more grids had torn in the same place. Now that's the 1st time that has ever happened to anyone I know of. My advice is to double check the seams if you have pentair grids. You don't want to be trying to vac out a pool full of DE. It's not fun and very time consuming.

 

[dehn0045]

I know this is an old thread, but there isn't a lot of information out there on this issue so I figured I'd add my experience. Pool built in 2018 with all pentair equipment, DE filter worked great for a couple years. Water quality seemed to fade late last summer but I couldn't pinpoint the problem. In hindsight my robotic cleaner was probably picking up a small amount of DE, but it was by no means excessive. I broke down the filter this spring and cleaned the grids, after this I started to see DE in the pool and excessive amounts in the robotic cleaner. Disassembled again today and noticed the bottom seams on all the grids completely open (exactly like the pic in the previous post). I called pentair immediately, the rep asked for a picture and after seeing it he immediately said they would send out replacement grids at no charge. However, I believe I am still in the 3yr package warranty (barely), so no sure what they would've done in a few months. I asked if this was common or something that I could've caused, he said no to both. My filter is an FNS60 that is stamped July 2018, so it seems like this problem spans at least several years.

 

[Nina.mypoolskeeper]

I realize this is an old thread but I had to reply. I service and maintain pools and have for over 7 years. I was asked to help out on a few filter cleanings by the pool owner and ran into my 3rd set of grids with bottoms open on all 8 grids in 2 pools and all but smaller grid in 1 pool. These are without a doubt defective from factory and is the first time I’ve ever seen this. I don’t believe most folks would have noticed the issue the grids appear to be fine when resting in grid housing, it is only when removed and inspected does it show. These filters all have a common builder and are Fns plus 48 they were manufactured in 2018

 

[ferretbone]

Everything is possible, of course, but I have lived in this house for 7 years with no problems. The pool has been in for decades with no evidence that the plumbing has been modified. In 2013 I tore the system down to clean the grids and that’s when I discovered somebody had put a mixed size set of grids in the old unit. That’s when I replaced the entire filter with the new Pentair. Has worked just fine with no leaks and was torn down last year with these same grids, no problems.

It’s a (expensive) mystery. Pool is clear as a crystal now.

The last person who put the grids back in didn't put them in correctly. I see that about once a week. I have also done it my self with old warped grid frames trying to get them seated back in.
When someone can't get the bottom of the grids lined up, and seated properly they have to push down hard on the top manifold. That crushes the bottom coners of the grids. That is very easy to do with older grids. You may not crush them in that moment, but they will break after they are under pressure.
If the bottom edges of the grids are seated on any of the pedestal teeth they break off inside the grid, or completly crunch up a few layers. Especially if the grids are older. The half grid is the easiest to line up, and offen times the only one installed properly. So that one usually makes it. Once the plastic inside the grid is cracked, it never takes long for the sharp inner frame to tear into the fabric. Thats how grids get broke and ripped up. 72's grids are the worst with this problem.

When the fabric is loose and no longer tight around the grid frame, that's from either over backwashing, to much DE, going to long without cleaning the grids, or all the above.

 

[JoyfulNoise]

Solution - don’t use FNS type DE filters. The QuadDE cartridge style DE filters are much better and have lower head loss than grid style DE filters. That said, when my filter gives up the ghost, I’m replacing it with a cartridge filter. DE is not worth the hassle and I doubt any average pool owner could ever see the difference in water clarity.

 

[JamesW]

These are without a doubt defective from factory and is the first time I’ve ever seen this.

Can you show the labels on the grids?

 

[wireform]

In March I was asked if filter grids need to be changed all while pool was still winterized. My response was why you asking this. Well last year pool guy mentioned you need new filter grids for next season. So I stopped over while all was still sleeping from winter and cracked open filter and saw a cracked manifold and I said this is all you need. Ordered it and when I returned to install stuff looked suspicious so I pulled more apart to find the "pool guy" not me must have been in there, pulled out the grids and never put them back where they'd belong and by forcing the manifold he cracked the manifold and broke some grids too. So then I ordered new grids, long story short put it all back together with new parts and instructed home owner to tell pool guy not to touch the filter when opening for the season. Fast forward, 2 weeks into the season I get a call and says you know the pump is running 2 weeks and the pool isn't clearing. I ask did the guy do anything......? they haven't seen him in two weeks. Ok I'll be over. Upon arrival psi was through the roof and pump bearing was screeching. I back washed the DE filter but guess what, the shm*k never put DE in. A new pump and everything else that follow TFP methodology...... and the new pool guy never let them down ever ever ever. Pool is still open slated for closing this week all because the water is perfect and still being enjoyed.