Last Minute Advice Before Purchase!?!

Help! 15" cube lighting is holding up my purchase!

OK, I've been saving to start a nano and I'm ready to order tomorrow.
I'm looking at a 18 gallon cube (13 in front, 5 behind false back) with 48 watt light system (2x24- 1 day and 1 blue), a fan, and protein skimmer.

The company originally also offered a 72 watt system, but it isn't offered anymore. Is this okay? The man says most of their tanks have the 48 watt system and are flourishing and have anemones.

I know I have to wait a while for an anemone, but I'd really like to try one at some point as I will have 2 percula clowns (I know they don't NEED to have an anemone)... Is this REALLY possible with 48watts?

Thanks!

Sorry! Power Compact!

The tank is 15" x 15" x 15"

It is a 18 gallon (13 in front of false back) cube aquarium. I can buy with or without canopy. It is a 15" cube.
The lighting offered for the canopy is 48 watts and I would like more than that. Do you have any suggestions for a retrofit kit or PC light that would fit??? I'm totally frustrated! I would like to have an anemone at some point and want to buy the "best" lighting now not upgrade later...

What is the max amount of lite recommended for this size tank. I would like to have fans and maybe a moonlight.

10:32 p.m. ***They (company I'm buying tank from) said I could do 2 of the 48 watt systems for a total of 96 PC lighting. Days/Blues. With fan and moonlight... What do you think???