Can someone please help me find a medium to high output light for an aquarium this size? I will be dosing CO2. These dimensions have been tough, most lights aquarium 18" or longer. Maybe some kind of clip on?
A "cube" tank, especially one that small, can be lighted with a small, but bright light suspended above the top of the tank. The light will spread out to give good light intensity over the whole tank. I have never used this type of light, so I don't have any specific recommendation for one.
If you are a do-it-yourself type, you can easily make a good LED light that will work well, too.
I have the same tank dimension and I have a Kessil A80 on it and it does a good job but It won't color red plants very well, its great for med to low light plants. The Kessil 160A should grow anything but if you want a less expensive option them get an 6500k LED light from ebay with at least 25 watts.