What would also concern me about those LED strips is the lack of spread...most fixtures designed for aquarium use have diodes packed pretty closely together so that you get light over a greater surface area. LEDs are much more directional than tubular bulbs, and you don't want a "spotlight" effect happening in the tank.
This is the LED fixture I'm using on my 20 long and it's considered low, barely medium, lighting...48 white + 24 RGB...pretty big difference between that and the number of LEDs on your fixture.
http://www.current-usa.com/aquarium-led-lights/satellite-freshwater-led-plus
If you're going with mostly mosses, you wont need much total light, especially over a 20 long which is pretty shallow. A few CFLs, a T8/T10 or T5NO fixture would be plenty.
This is the LED fixture I'm using on my 20 long and it's considered low, barely medium, lighting...48 white + 24 RGB...pretty big difference between that and the number of LEDs on your fixture.
http://www.current-usa.com/aquarium-led-lights/satellite-freshwater-led-plus
If you're going with mostly mosses, you wont need much total light, especially over a 20 long which is pretty shallow. A few CFLs, a T8/T10 or T5NO fixture would be plenty.