Hi B.,
My husband and I have a pool and hot tub in our back yard. Maybe I am not paranoid enough but I've taken all 3 of our kids in when they were babies. They were born in March, April, and May so they were all pretty small their first summer. I mostly took them in the hot tub as I was afraid the pool would be to cold for their little bodies, but that was the only reason. They all loved the hot tub, I think it just felt really good to them. Of course, make sure their head and face don't go in the water, and you can pop them right in the tub after to wash off the chemicals. I wouldn't worry about it if I were you, just have fun with them :) They are a little more vulnerable as us, but not much, they have the same skin we do! Just put sunscreen on him the same way you do for yourself!
Have fun and enjoy what's left of summer!
V.