Replacing an O-ring

Hey,

I have a leaky o-ring on the top dome of my Hayward S200 sand filter that I am ready to replace.

Anything special I need to do to remove the cap to get to the o-ring, other than shut off the system and unscrew it?

Thanks,
-A

That's pretty much it.

Clean the sealing surface and use a Teflon or silicon based lube on the new o-ring. Clean out the threads, if they have any junk in them.