only thing is most kessil should be mounted 8-12 inches above the water to get maximum spread
on the 14 gallon nano with it only being a couple inches above the water, I dont think this light is ideal for tank or set up.
its really not the question of weather the light will be powerful enough, it sure will directly under it, just led are like lasers, especially only a couple inches above the water.
with that size tank and for the price i g with t5. you will be able to grow anything you wat all over the tank