Hoping to finally hook up my 2 500gal storage tanks to the primary loop soon. I also plan on using a 250gal used propane tank mounted vertical as my expansion tank. Someone here mentioned modifying the propane float to indicate water level and I may do that. If I could get my hands on about 10 feet of any size clear O2 barrier pex, I think I would rather make my own sight glass. Anyone have any they want to sell or point me a place I can find some?