Thanks. You are a plethora of information! I should probably look online but it seems some of the online information has not been quite correct. Would a regular ball cock style float valve for a toilet work. I was a maintenance man for almost 10 years and have worked with hundreds of them. I could rig one to work with a top off tank. What I am going to do is take a half inch dowel and use it to mark off the depth of each gallon for each tank when I change them out in two days so I know exactly what I’ve got in there until I do a float valve set up. That should help with what I need to top off the tank until then.