I would give it a try at those temps. It may take a little longer, at least for your first batch. I'm using rainwater collected from my roof and gutter that have oak leaves, somewhat aged let's say, so my water has a slight tanic tint depending on the recent rainfall volume. IMO, I would collect out of a clean stream before using even aged treated water.I should start making my own AACT soon. Right now even though during the day temps are around 67, they drop around 50 during night (sometimes below 50).