Running wire for float switch

I was recently digging the ditch in preparation for the following water system and had a quick question regarding the size of the wire that will be controlling a submersible pump via a float switch... There will be a primary spring filling a 1300 gal storage tank above a secondary spring with a larger storage tank. The primary storage tank is 340' distance and 90' of head above the secondary tank. The primary tank will gravity feed the home, but during low flow time of year I will need to pump water from the secondary tank (which is the same elevation as the home) up to the primary tank. I will bring in professional help to set-up and wire the system when I get there, but for now I just need to know what size and type of controller wire I need to run between the tanks to control the pump with a float switch?... remember 340' distance.... underground. Some one recommended running it through 3/4" conduit since even direct bury wire is prone to damage and eventual failure over time. Thanks in advance.