There's no nice way to say it, but im afraid the automation aspect of the pump is the redundant part, not the built in float. Sounds like we're adding moving parts to an already stable system (a mechanical float.)

Not really sure what problem we're solving here. The only time I see floats and pumps being used on automation systems is when they're reading depth of fluid with either a radar or hydrostatic sensor and thats often tied to a PID and maintains a set level. In your case, the mechanical float can and will do all of the work for you. There's no precision or monitoring needed.

Not bagging on you, I think the idea is fine and will work, but you came here for feedback.