I used to empty the bucket and purge the lines after every fill. I recently started using Water Wetter with the cooling water and leaving everything set up ready for the next fill. Water Wetter has additives to help prevent mineral deposits from forming and "funk" from growing in the water. Water Wetter does not inhibit heat transfer like antifreeze. It is supposed to help heat transfer but I have not noticed a difference (I use it for the other properties stated). If you want to leave your unit set up I would use distilled water (no mineral content). There is not really anything in the pump to corrode; plastic and a magnet. You can also get a replacement pump at Home Depot for about $17 - tile wet saw pump.