Next time you see the level in the filter getting close to tripping the float switch, shut off the skimmer and see what happens. Depending on your setup, it might not affect the level that much or it might run for 30 seconds while the water level is dropping back down.
If that's the culprit, you have some workarounds:
1)Raise the filter so the skimmer shutting off doesn't cause the problem.
2)Let your skimmer run all the time.
3)Raise the pH it needs before shutting off so it happens less often.
4)Have your filter roller shut off whenever the simmer is turned off.
Any of those should be pretty easy. If I were you, I'd let the skimmer run 24/7, at least until you figure out what the problem actually is or at least rule out the skimmer as the culprit.
Also, as I'm thinking about it, if the skimmer is the problem and if the pH controller shuts the skimmer and filter off, when they're powered back on, it'll take a few minutes for the water level to come back down in the sump. You'd have to have it delayed by a minute or two. BRS sells
something that does exactly this for a very similar application. It's meant to delay your skimmer powering back up so the return pump can get the water out of the sump before the skimmer fires up. It would work just as well to delay the filter turning on. But at this point you're throwing money at a problem that could be fixed for free.j