Question about ro/di and ATO

[gobytron]

I'm finally moving away from the aquarium pharmeceuticals tap waer ro/di filter and setting up an automated freshwater top off system.

I use a tunze osmolator but I am going to be setting up a kent float valve hooked up to a 3 or 4 stage ro/di filter.

My question is aside from the ato, the float valve and the filter itself, what other component do I need?

will any ro/di work or do I need to purchase one specifically set up for an automatic top off system?

Links and advice greatly appreciated.
Thank you.