The website is not the best, but once you got "buy tickets" you should get a calendar that'll tell you when the tubing is open. Also, always book online in advance as the slots fill up very quickly. Don't rely on buying in-person for the same day, this is a very busy place.
Beside Friday thru Sunday, it is open on Holidays and School breaks. It is open during Winter break and mid Winter break. There is calendar when you buy tickets online.
Thanks! Your answer is awaiting moderation.