First up, Welcome to AA. And, just so you know, there are no dumb questions here. Either you know it, or you don't, and if you don't, you ask, which is why we are all here.....to ask and to help everyone else.
That being said, I have one for you. What do you mean by the overflows "high and low"? Do you have 2 overflows?
In a normal system with over flows, the following is what happens when the power goes out:
1.) The water drains out of the overflow until the water level is below the overflow
2.) AND out of the return until the return is above the surface of the water, which breaks the siphon.
Now, if you have a submerged return, it is PARAMOUNT that you have enough extra capacity in your sump to hold the overflowing water. If your sump will overflow before your return siphon is broken (this happens when it is above the water level) then you need to modify your return. Most people find it simple and effective to drill a hole in their return line, just below the surface of the water.
Tell us more about the overflow, and a pic if you have it. I'm confused about the "high and low." HTH