Home Depot only has playsand and concrete, Walmart has nothing ( I live in a town of 25000, we just have the basics ) I went to a water store my neighbour works at who sells hot tubs pool stuff, but they dont have filter sand, he suggested another place on the other side of town but I'll have to ask again. I still got a few days to research.
Hoping someone with CFL does chime in, according to that post a 15 watt CFL bulb 15 inches from the light to the bottom of the tank is ~110 PAR, and they stat anything over 50 PAR needs co2 :/ I hope I'm reading it wrong
Read this on CFL's, it helped me out greatly when I had two 23W CFL's over my 20g (I now have a FInnex LED):
PAR Data-Spiral Power Saver Bulbs, lighting question