Grid failure on Pentair DE filter - Causing DE Leak [Update]

mktee · Nov 6, 2023

I just encountered the exact same issue (link to original post below) on a <2 year old FNS Plus 60 DE filter. I opened it up this weekend to do a full cleaning and noticed the bottom of every grid was blown out and completely open -- looked like they were wearing wedding dresses when I was rinsing them. I didn't see any evidence of frayed string from the seam so suspect they were glued together and the glue must have sucked. I put them back in taking extra care to fold over the mesh to create the best seal possible but it didn't work. I have DE coming through the jets, mostly when the pump starts, and it's collecting on the pool floor.

My pool has always been well maintained. Pressure is consistently around 9 PSI except in spa mode and then can get to 18 psi max. The chemistry is monitored regularly and is spot on. This is my third Pentair DE filter that I have maintained. Never any issues with them until now.

I called Pentair and am waiting on a response regarding the warranty. My builder didn't register the equipment like he said he would so I had to go through that process today. Hopefully they send me replacements under warranty!

Moved from here.

wireform · Nov 6, 2023

Did they perhaps reverse hook up the inlet and outlet to the filter as that can cause what you have going on.

JoyfulNoise · Nov 6, 2023

How often do you backwash those filter ?

At what pump speed is it backwashed?

What is the filter pressure during backwash?

mktee · Nov 6, 2023

wireform said:
Did they perhaps reverse hook up the inlet and outlet to the filter as that can cause what you have going on.

Thanks for the input. I verified the multi-valve is installed correctly.

mktee · Nov 6, 2023

JoyfulNoise said:
How often do you backwash those filter ?

At what pump speed is it backwashed?

What is the filter pressure during backwash?

I rarely backwashed the filter because the pressure always stayed the same. Maybe twice since the pool was started in 2/2022.

The speed during each backwash was probably around 2600-2700 rpm.

I don't recall the pressure exactly but think it was in the 10-15 psi range during the backwash.

mktee · Nov 7, 2023

Update: Pentair is sending a service company to correct the issue under a warranty claim. I assume it means grid replacement but won't know until I meet with them.

mktee · Nov 10, 2023

I spoke with the pool service company Pentair assigned to the case and he said this was the second time he had seen this issue and the first time was just two weeks ago. They ordered a new grid assembly and said they should have it ready to install next week; all under warranty.

I would suggest to anyone having a <2 year old FNS Plus filter perform a thorough grid cleaning to inspect the mesh bottoms for separation ahead of the warranty expiring -- even if there is no DE in the pool.

I didn't have a DE issue until the first time the grids were removed and reinstalled. It looks Pentair used glue or heat to close the mesh and it didn't hold. When the grids were removed and put back in the mesh did not line up together as it originally did from the factory causing the DE leak.

I am very pleased with this outcome and that Pentair is honoring their warranty quickly and without any hassle.