Nope...that lighting is nothing on top of a 20" deep tank. IMO, a 20" tank is grounds for metal halide. PC lighting, especially only ~43 watts just cannot penetrate that much water. And seems how the tank is only 15"wide, you cant really fit a power compact fixture that has any punch either. Hexs also have the downfall of lacking sufficient surface area for necessary gas exchange, etc.
i hope that this helps. I would suggest picking up a AGA 10 gallon tank at your local fish store for ~$10 and you will be much happier. Its 20"Lx12"H and you can fit a fixture like the Coralife 20" "Quad" that will give you 96 watts of lighting...then you will be able to keep most any coral...other than high light-demanding corals.
and... WELCOME to nanotank.com
Jesse