Hi guys, i am thinking about getting some ada soil, will the three liter bag be enough for a 5 gallon hexagon? If not I don't want it and will use the cat litter sand method 
Don't forget to cycle the tank for at least two weeks before adding livestock.
Add plants to help the cycle.
That's not a suggestion, that's a must. Plant heavy, and then just let the tank sit for 3-4 weeks.
If you've never used AS before, it can be a little scary right in the beginning. Your water parameters are all over the place for the first month with AS, but it stabilizes into awesome, so don't worry.
Do it Amano style, dry plant, and then fill up slowly over a plate/frisbee to prevent cloudy water.
The guys at Aqua Forest gave us(SFBAAPS) a demo today about working with AS, including some hints they got from Amano on their last trip over to Japan.