I wouldn't go with a pump under 65 gph. You can usually dial down the flow, but you will quickly find that you want more water. I started out with a 30 gph and quickly worked up to a 120 gph fountain. Even in my 10 gallon terrarium, I have a 70 gph fountain pump.stevendart14 said:I was looking at some fountain pumps and was thinking was 65 GPH to much for a waterfall in a vivarium. I also seen a pump that was 145GPH and that seen like way to much power.