Guys made a HUGE bath bomb and dropped it in a swimming pool!

I gotta admit, I've always been intrigued by these bath bomb things since my wife started using them haha. I love getting drop them in the tub and watch them work. They're crazy to me! Then these guys did what I would've LOVED to have done - and made a GIANT one! A few questions here....how did they make this? And do they have to clean the pool now, or what? Hahah this video is pretty darn cool....totally worth wasting a few minutes of your day watching!