Secondary supply pump for skimmer use a timer?

[Old Salt 64]

I'm going to use an Octopus SRO-3000 EXT skimmer and run my supply pump in my sump next to the return pump. I've never had to run two pumps on a skimmer before but I plan on getting a time delay on the skimmer pump and wonder if I should do the same for the supply as it only makes sense and if I do why can't one run both pumps on the same switch plug with an adapter? Or is that too much voltage on the timer?

If I don not put the supply pump on a timer what are the consequences of supplying water to an external skimmer that is not running? Overflows? Leaks?

That's my main concern.