I have six of these Hydor Smart Level Controller available, $70 each. They’re hard to come by this model for this price!! They are unused, new-in-box. Currently selling on Amazon for $120 if you can catch them while in stock:
I’ve had the best luck with these controllers when paired with a Marineland Maxi-Jet 400 powerhead pump or smaller Taam/Rio powerhead pumps. Lots of flexibility depending on the size of the sump or tank you want to top off, but you’ll need to read the manual for the controller, there is a time limit to how long it will keep the pump engaged.
PM with questions, I usually respond pretty quick.