I cannot get my chlorine level to go up. They are normally around 4-5 ppm and last week they dropped to 0. I dropped in a pound of Dichlor last night and chlorine shot up, but was gone about 3 hours later. The pool is small at only 6000 gallons. The T15 SWCG is now at 50%, clean and voltage/amps are 25v at 7.3 amps. Any idea what I'm missing? It normally ran in the 20-25% range with no issue and is only 4 months old. Below tests are after running at 100% for 8 hours last night. Water is very clear, no visible signs of algae.
Salt: 3500 (just added over weekend as it was down to 2800)
Pool store suggested superchlorinating at 100% for 24 hours and re-testing.