I decided this was the route to take: float

I ended up at my local hydro store today and discovered that they carried the exact same float for 3 bucks cheaper and no shipping like I had to pay. On top of everything else, I got an email this afternoon saying they wouldn't be able to ship it for another week. Oh well. I wasn't really ready to start construction anyway.

As to this float that I got; The float part is adjustable to a degree and can be installed vertically or horizontal according to the site. The way I intend to do this, is to install this float via a bulkhead method. The float comes with a rubber washer and looks like it will attach quite easily through the side of my tote. On the other side I will connect a 1/2" black rubber line that's used very commonly in hydro. I will run the line up a few feet into another res that's about 5 gallons I think. I will probably not even plumb it and just feed it in through the lid. I think gravity will do a fine job siphoning and create an autofill for me. The store clerk and I got into an interesting conversation about whether or not he thought this float would be able to stand all the pressure from 50 gallons of water, but I think we both assumed I would be plumbing it through the bottom of the top res. By running it through the top of the res I can avoid having all the pressure on this float valve.

To accompany this gravity fed line I will install another line with a pump attached that will sit in the bottom of the root zone res. About twice an hour I can start the pump, which will pump water up to the top res, which will begin to lower the bottom res and thus trigger the float. The valve will open and the top res will begin to fill the bottom one. The float should also open every once in a while to fill the bottom res as the water gets used up from either the plants or dehydration.

Since the top shelf is easily 6 feet high, I will have to use a pump capable of handling all the head pressure.

Thoughts?