I used a Borneman (toilet flapper) surge. My plan was to have 2 5g buckets at each end of the tank, but in the end only got around to one. The plastic chain I used to hold the float was constantly getting stuck on itself or the ball would wedge itself so it was stuck open or stuck closed a good 1/3 of the time.
If I were to do it again I'd go with a square tank and larger so that it wouldn't be prone to this.
Other than that it worked well. I drilled the pipe near the outflow and put a little tube into it for letting the air escape and that cut down on the bubbles a lot.
It made a really neat "kerploosh" sound when opening.
I voted that I would do it again, but the truth is I'd give a Carlson surge an equally viable consideration as well ... without moving parts I think it would be more reliable. At least when it failed it wasn't a disaster as there was an emergency overflow but still, you want to know it's doing its thing and not just sitting there trickling away into the tank.