upon replying to another post reminded me of something.
I was at a client's home doing a repair years ago, while in their bathroom i noticed pictures of their children outside with streams of foam and bubbles coming off of them.
I asked the homeowner what the pictures were. A GREAT IDEA! she said when they're ready to change the spa water they pour a whole bottle of bubble bath in the spa and let the kids go in. It's hilarious, my kids go bonkers over this.
We've all seen willy wonka and the part where they ride the soda/ foam truck. foam just pours out of the spa onto the deck, the kids can't even see each other.
Yes, a bit of flushing is involved after draining, but the experience for the kids and the look on their faces when the foam starts flowing is absolutely priceless.