you are absolutely correct, lindsayanng! :coolgleema: dave simply misunderstood how cold it gets over where you are and the fact that you would need almost arctic conditions to support his theory of freezing waterfalls. so yes, if you leave your waterfall running, you will be fine and able to enjoy it during winter (but don't forget to insulate those pipes! :icon_smile. unfortunately, it seems that when i corrected dave, he took it as a personal attack; i apologize for any negativity he's brought to this conversation, and hope it doesn't prevent you from becoming more involved in our forums! thanks for your question, and i hope that helps! :banana: