Hi Carrie,
For a 26 gallon tank, you may want to consider using 2 smaller powerheads instead of one larger one. All depends on what other forms of water circulation you have too.
But I would think that using (2) two MINI-JET miniature powerheads might work out nicely for your tank.
Model MN606 ( 82 to153 gph ) cost around $23.00 each.
These are small, and have a sliding adjustable plate to adjust the flowrate. This would be my preference over the Rio's.
It's an option for you to think about
Get two of them, mount one located down deep on one side of the tank, the other one up near the top on the other side - pointed at the surface.
The MAXI-JET powerheads are nice too - although they may be a little large for your set-up.
Depends what you are keeping in the tank, and what you want to accomplish.