Hot tub deaths do happen. He probably had an extremely weak heart after years of abuse currently clean or not.He's been supposedly clean for the last couple of years. No drug paraphernalia found at the scene. Obviously people don't usually die in hot tubs so some type of medical issue caused it.
Likely had a heart attack from all the substance abuse over the years. He's had some health problems for a number of years.
Guess we will see when the coroner's report is released, as they are going to do an autoposy.