Do not put the antifreeze in the main water tank! You will use way more than you need to and it will be difficult to clean the pink stuff out come spring. As was suggested, you can make a winterizing system by attaching a hose to your pump inlet and putting the other end of the hose in jug of antifreeze. Then you can pump the antifreeze through. You can make it permanent by adding some valves. Don't forget to drain and bypass your water heater first.
Seasonally in the Grand Marias, MN campground
On the beautiful shores of Lake Superior
2012 Ram 2500HD CTD