I have an above ground intex pool (3800 gal) with a SWG. I have had it for about 1 month now and havn't had any trouble maintaining the levels. Now, my chloring keeps reading <1. My SWG runs for 5 hours and shows no indications of problems. I have also added bleach recently. The CYA levels are reading normal, but I don't know why the chlorine level is so low. Any suggestions?