I'll keep that in mind. I think it ended up around $15/bottle, so I'm not exactly sweating the cost of buying more than I needed. I had another thought after my last post. I poured it into my piping through my dismantled sidearm piping, which amounted to a standpipe with a ball valve & half a union on top. I haven't put it back together yet, so one side of the ball valve has been open to the air since I put it in, and I did spill a little bit when I did it. I wonder if that messed my ball valve or union threads up, with hardened/dried Gunk? I guess I'll find out soon enough - time to put that circuit back together. That's this weeks chore. Worst case I'll need to get a new ball valve & union.