solar hot water antifreeze tip and pressure trick

I have one of the largest residential solar hot water setups in CT. How do I know this? because nobody is silly enough to make their solar setup 3x bigger than it needs to be. One issue I had years ago was a antifreeze PLUG which happened one night when it got cold, -7F if I remember correctly. antifreeze at 50/50 is pumpable down to 0F ... below that you have a problem. Once the stuff freeze, the pump can't run, and eventually the pressure goes high enough to blow off the pressure valves... this is bad because you may not know when this happens, and then you won't have enough antifreeze in your lines for proper heat transfer. Ok, so, in new England, run a 75% antifreeze mix. Pressurizing the lines was a pain until I got my soda/acid fire extinguisher.... now its easy. I'm sure there are other ways to do this, but this is the best for topping off the system. I think there are about 13 gallons of fluid in my setup total... and since 5 gallons of propylene glycol is $90 ... best not to waste it. When filling the system I just fill a Rubbermaid full of fluid, and then use a cheap drill pump to prime the system...once the circulator "catches" ... it fills on its own, but it won't pressurize the setup without a pressure device such as this. leave comments and suggestions if you like!