I am having a sunroom built and they are repouring my concrete. My tub was drained and I spent a couple of hours getting all the water out with a wet-dry vac. Here it is 2 weeks later and I still have no slab (weather and an over-booked concrete guy.) They are now supposed to pour on Wednesday, but it is supposed to rain again. I am afraid of my shell cracking from the heat on the days that it is not raining. My dealer suggested that I fill my tub with super-chlorinated water, but won't it get funky anyway from not circulating. So far the hottest I have seen in the tub was 88 degrees. It was at 5PM on a day that the high was 86. I have since put a canopy over it so it is in the shade. How hot does it have to get before I am in danger of cracking? I really don't want to have bacteria laden water stagnating in my tub if I don't have to. I would appreciate any advice.