we will be adding balloons to the pool for decoration. 
There is no AC in the house, and the wedding is in June, so it could be a heatwave. I am more than happy to have people bring their swimsuits and change if they want to cool off. But I am a little concerned the older guest will think of it more of a pool party than a wedding?
However, I would MUCH rather people enjoy themselves and take advantage of the pool, but i also don't know how to bring it up to people, "its a wedding but bring a bathing suit because we have a pool" ?