I'm glad you found something helpful here.

I find it frustrating that puddle pools are sold without any hint about how difficult it can be to keep them clean and safe!

If you limit the number of swimmers, add bleach as described, and drain and refill regularly . . . you'll be MUCH safer than otherwise. I'm not sure about the UltraShock -- so many pool chemicals now are compounded from a chemical 'voodoo soup', that know one knows what's in them, and some ingredients used can cause real problems.

I'd encourage you to use the PLAIN 6% bleach, instead of some "UltraShock" with unknown ingredients. Because of the way 'shock' is labeled, it may NOT contain ANYTHING that kills germs effectively!