You can feel free to post a link. That is not against policy here. The only problem w/ your float switch is that if the float ever fails it will put 110v directly into your tank. This can be said for a lot of equipment in the tank tho.
I just so happened to order a bunch of stuff to make a latched switch setup. I am going to have my topoff above my sump outside the house in a garbage can. It will gravity feed thru my kalk reactor, then to a float valve. There is a float switch in the bottom of the can and one at the top. With a relay you wire it all up, and you use a 12v power supply wired to the float switches, to trip the relay, and it switches a 110v power source to open a seloniod, or trip on a powerhead. Anyway what this does is when the water gets to the bottom of the can it trips the bottom float switch, opening a silenoid for the rodi. Once the can fills it stops, and waits till it gets to the bottom again. The benefit of this is that it lets the rodi run for longer then a minuite or two which is bad for ro membranes. There are ways of doing this w/ your type of top off too so that you will only have 12vdc at 500ma that could ever go into your water thru the float switch.