This is nice but two things.
You shouldn't use windshield wiper fluid. Should anything fail and spill out during maintenance or failure you could do harm to your chickens. Use Propylene Glycol instead. It is food grade antifreeze.
Next you could have done this with a single $12 pump, a single $2 limit switch, some $5 tubing 3/8" ID and some 1/2" ID, and either a $12 SPDT timer or 2x $11 SPST timers.
This is how to do it with a single timer. Using a single timer will mean the timer stays on all day but they don't use too much power anyway. Either way you don't need to worry about setting times to account for fill times. The eight of the water and the limit switch will cut off the pump as soon as it is open. When the timer turns off the power to the pump is turned back on and the bucket starts to fill more until it passes the 1/2" ID tube and it starts to syphon. Once it starts and the water is being syphoned faster than the pump can fill it the weight drops and the pump turns off. Bucket empties.
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