They have the timing specified their website with the calendar. Generally on Saturdays it is 11am -1pm, 1-3pm, 3:30pm-5:30pm but you would want to check the date and availablity. As the tickets are first come first serve and each session requires you to purchase the tickets 30 mins prior and can only be purchased in person. Tubing generally has a long line and you would have to wait as it's open only for a few hours when it's operational.
I was there last Saturday at 4:30, I had to wait in line until 5:30 for them to start selling tix for the 6-8 slot. I had a better experience on a Friday night
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