Last summer I had to replace the pressure gauge/release valve on a Pentair 100c filter. When we opened up the cap (which was a 6 hour awful task) the inside of the filter smelled horrible, and I could see the inside of the filter was a pretty big mess. This is a free community children's pool that gets some heavy usage, so I am assuming that I need to change the sand. It has not been changed in at least 10 years. Possibly in more than 15 years. Could be as long as 30 for all I know. Also, the laterals may need replacing as the filter does have sand shooting issues, and has for a while. My first question is, am I correct in assuming that the Sand needs to be replaced?
Today, I went to take the caps off the filters so I could dig out the sand, (there are two children's pools), but I couldn't. Both pools, the cap is stuck on there. I tried using a hammer and a wood block with the filter wrench with no luck. Last year it took three of us to get it open and I have somebody coming to help me tomorrow, so hopefully, I can get it off. My second question does anybody have any ideas or advice for getting the caps off?
Finally, the 100c is a big filter, and that seems to be a pretty small hole in the top. Anybody have any experience with this model? I'm not totally sure I'll be able to dig the sand out, or reach in and take out the laterals to examine them.
Also, additional information, one of the filters has had it's cap replaced with a different model cap, and no, I do not know why somebody would do that.