My filter was installed 2 years ago and I need to replace the original dex2400k (d-ring)
I ordered and installed a replacement o-ring and that leaks, also seems not thick enough.
I realize (now) that these are sold as O-429 replacements.
I have now ordered 2 dex2400k d-rings at poolsinc.com.
I will find out if they really are d-rings (not o-rings) when I receive them.
Really ****** at Hayward, but my fault for not doing proper research before
getting this system. If I ever buy another whole filter it will definitely be
a pentair.

Welcome to TFP!!

I started this thread to inform folks, like yourself, of the issue.

I'm sorry your new o-ring didn't properly seal the filter (as I said to Waterbear, the 'off brand' replacements often weren't thick enough to seal the unit )

You can try Pogo and Ohm_boy's suggestion of making your own.

If you have other issues, once this is fixed, please feel free to ask me

Well I got my so called D-rings from poolsinc.com and they were O-rings instead.
Now what?

i am really surprised this is an issue. i have never had to replace a tank o ring in my 10 years of service and repair.