I have a Rainbow 320 Chlorinator. This is a top feed - the water flows out from the top over all of the chlorine tablets.

Last week I noticed that I had more chlorine left than expected. I thought that was funny since we're in the middle of summer, but just shrugged it off and made a mental note. (All other levels were appropriate; nothing out of the ordinary.) Today, I replaced chlorine again and noticed the same thing. After replacing the tablets, I normally wait and let the water fill up all the way and then screw the cap on top to prevent air from getting into my lines. However, when I waited today I had to turn the dial all the way up to maximum (#5) and it still never filled up.

I checked skimmer baskets/drains and there is no physical blockage. Also checked CYA levels and they look normal. I do note that I have a high level pressure in my filter. (30 psi) A couple of weeks ago we had a lot of small insects that got into the pool (ants) so I think that's what is causing the high pressure.

Could a high filter level pressure be causing my chlorinator to not fill/dissolve tablets? Any other ideas? Any help troubleshooting help would be greatly appreciated!