nitrates

I have a new pool, 4 months old. Hayward T15 swg. I cannot keep the FC levels up despite running the cell at 95% for 12 hours a day for the past month straight. CYA is 55. Ph has been at 7.4 for months and I have added zero acid. TA is 80. Salt is 2900. I have suspected that I have a bad salt...