I have my own test kit (TL 100) that I have been relying on. Both pool stores have come back with different numbers every time. I don't give them much credit when it comes to testing my water. lol.3 days is very short for water that’s green. You may not have any chlorine loss depending on how you are testing it. The OTO test or the pool store aren’t accurate enough for that.
I will start back at the beginning with the slam and go from there.