semi inground pool

Hello , I have a saltwater 8000 semi inground pool 15x26x54 oval. With Hayward Aqua-Trol/T-Cell-5 (20k gallons) My pool is 1.5 years old. And first cell went out in 6 months, bought a generic cell, and used it but then Hayward finally replaced cell, so changed out to the new one ,that one...