I have used the compressed air method for many years. This past winter, the extreme cold found that I hadn't gotten all the water out of my diaphragm pump and it split, also the top of two twist lock Heads had cracks even though I had used the pink stuff to winterize, apparently there was a bit of water that dose not drain at the top of the pump, also the pink stuff makes the rubber swell. This year I will remove the pumps completely and store them at home. MARCY Kha Shing 36 MI