First off, this is my sand filter: Hayward S200 side mount with clear plastic dome
Background: The sand filter was not leaking before we deep-cleaned the sand by unscrewing the plastic dome on top, running water into the sand, etc. Unfortunately, when we put the dome back on, it began to leak from the dome. Not a horrible leak, but visible and worrisome.
So, we bought a new o-ring, cleaned out the threads, added new lubricant, put in the new o-ring, and put the dome back on, tightly. Turned the pump on, and it is now REALLY LEAKING. Badly.
Yes, the dome is on tightly. Yes, the o-ring is seated correctly. Yes, we used pool lubricant. I believe that there must be small fractures in the threaded area near the dome, and that they got worse the second time we messed with it. I'm at a loss as to how they suddenly occurred -- apparently, just unscrewing the dome was enough to cause them? At any rate, we're looking for solutions that don't involve dropping $800 for a new filter.
Do we have any options? Is it a good idea to just replace the top half of the tank, since that's the part that leaks? I've read here about 2-part epoxy, but if every time we unscrew/replace the dome it causes cracks, I worry that it will just get even worse.