I have inground fiberglass pool with 20900gallons and Pentair FNS PLUS 60 filter. Pool was build in 1989. We broung the house and the pool came with it. No previous experience with pool. Pool is green and tried and tried chemicals from Leslie's pool recommendations... I received my TP-100 test kit today and excited to get my pool back to sparkling!!! My CYA is 0 my CH is 1075 and TA 120. I have little or no cholorine in the pool. I have read the directions for SLAMMING my pool and have the liquid chorline ready. My questions is do I start with the clorine and SLAM as the pool math calculator has indicated or is there something else I should do before starting this process. I am exhausted on spending $$$$ for chemical that are not working.