All you need to do is clean it out with a mild detergent and rinse well. In maintaining your aluminum pot, I'll directly quote John Palmer from his book, "How to Brew".
"Cleaning Stainless Steel and Aluminum
For general cleaning, mild detergents or percarbonate-based cleaners are best for steel and aluminum. Bleach should be avoided because the high pH of a bleach solution can cause corrosion of aluminum and to a lessor degree of stainless steel. Do not clean aluminum shiny bright or use bleach to clean an aluminum brewpot because this removes the protective oxides and can result in a metallic taste. This detectable level of aluminum is not hazardous. There is more aluminum in a common antacid tablet than would be present in a batch of beer made in an aluminum pot."
This is a highly recommended book. It will answer just about every basic question you could have and plenty of advanced questions when you're ready to venture deeper.
