Yes, but instead of a controller, all you would have to use is a float swich to turn off, and on the solinoid, so you can let water from your R.O. pass through it.
That style is for if you are going to use it on a R.O filter. If you allready have a top-off, then like I said all you would have to do then is connect it in line, it is as simple as that.
Maybe we can jump up to a 4 footer, if you would like. I think that you would be happy with the 3 footer, though.