In the past, I sometimes entertained guests, on a special occasion, by adding bubble bath to my spa. It is a 500 gallon spa attached to the pool, so once the spa is off, all its water gets re-mixed with the pool water (16000 gal). I would pour a whole bottle of Mr. Bubble in the spa while it is running (with the usual spa jet turbulence turned on). If you let it sit for a half hour or so, you get a mountain of bubbles about 6 feet high, over the entire spa, People would love to get in the spa, and form caves under the bubbles. Adults seemed to love it as much as the kids.
I did this rarely, no more than once a year (e.g., New Years eve) because I figured it can't be too good for my pool chemistry. I worried about it adding phosphates or other stuff that would mess things up.
Just curious - how bad is this for the pool, as a very rare indulgence?