It's that way on mint too. I never circulate lake water on them anyway. I installed an internal circulating pump, with a timer on it, something they should do at the factory. I plug the drain, fill to the top with tap water, and put the blue chemical in it. When the weather starts getting above 70, I carry plenty of frozen water bottles. Put one of those in if the water gets above 70. I have a small thermometer to check often. It'll keep em alive from one weekend to the next as long as u keep the water cool, and keep the charger plugged in.