First off. SUPER helpful thread. Lots of great information here, but I didn't see anything that helped with my current question and I don't super feel it needs its own thread.
So I'm building a custom planted tank, low to moderate light plants, moderate planted density, no CO2. Its a tall tank though, and I'm not sure if I should get the nano or the 15". the dimensions from water surface to bottom of tank are 15" wide x 18" long x 20" tall. I think the nano in tall mounted position should be enough but I wanted some quick opinions if possible.