I have a chiller, but also keep water bottles with RODI water in my freezer. If I'm home when the chiller comes on I put ice in the sump to reduce my electricity use. It usually makes the chiller turn of in about 10 min.
I still don't have my under-the-house system hooked up to my main tank, but am hoping that it will keep the temp more stable when I do. It's on my list for this weekend after I finish fixing the sprinkelers.