Long story short, I have been battling with keeping chlorine in the pool. From what I can tell, everything seems OK.
FC seems to be steadily going down for whatever reason but never more than 1 ppm overnight.
I inspected the cartridge filter and there is a small crack in the top of it. Could this be causing the issue? The manufacturer is supposed to be coming next week to replace it. Also, the SWCG has been tested and is fully functional.