Can any tell me how much coolant it takes from empty to safe area in the overflow tank?

My tank needs to be removed and scrubbed...something I'll do in the fall. There's just too much going on right now to tackle that project now.

As you may have seen in a previous thread, my overflow tank was full. The sight glass was stained and hard to read....it appeared right in the middle.

I siphoned out the overflow tank tonight, and removed 2.5 quarts of coolant.

Does anyone know how much it takes to get it in the safe area?