Hi all! OK, I have been reading and researching and I am ready to dive in. We have owned a small 18,000 gallon inground pool since 2016. This year (a week ago) when we opened our pool the water was almost black. It was really filthy. I took a sample to the pool store like we have done for the past two years and they gave me 12 bags of shock, a bottle of algaecide, and Bioguard pool open complete. We did this last year and it was fine. This year the water just wouldn't respond. It did slowly clear up but the water remained a greenish color. I have since been back to the pool store two more times. They informed me my water is chlorine tied. Friday they had me put in 15 gallons of liquid shock and then my numbers were still bad yesterday so they gave me a non chlorine oxidizer (4 bags), and I was to put another bag of shock in today. It is still slightly greenish, and I am supposed to take another water sample back in tomorrow. Just no. Done. I have already spend over $200 and I'm sure if I go back tomorrow I can add to that. I need to get a better water tester. I am currently using an hth kit that I have no idea if the readings are good. Any advice on where to start and what to be looking at? I have been reading through a lot of this and would assume I am going to be told to partially drain and refill? For reference, at the pool store at least, my CYA levels were low. They were also reading low with my hth kit. Help is much appreciated!!