Everything was working well...chemistry good. One day low salt came on. I had added about 2 inches of water to my 15 ft. round intex pool previously several days before light came on. I added 6 lbs salt but light stays on, Ended up putting a total of 18 lbs all together and the light remains on. I run the pump 3 hrs a day, chem strip shows very little clorine. This is my 2nd years with this system and I cleaned the electrodes as recommended after last season. Any ideas on this problem? thanks, jim