2 batches... lack carbonation

Well my first batch of root beer I made was 2.5 gallons using gnome extract and granulated sugar. The directions said to bottle immediately and let sit for two days. I did that but a few bottles weren't completely firm until about 3-4 days so I let those ones sit. The root beer had so little fizz that I didn't like it... luckily the kids still did.

For the second batch using the remaining gnome extract I doubled the amount of champagne I used the last time thinking maybe not enough yeasties caused the lack of carb. This batch came out more carbed then the last batch and I and the kids like it. However it could definately use more fizz. I would really love to see a nice fizzy foam head one of these days. Especially since I like root beer that has a real bite to it. Bottles had been in about 75 degree temperature and I don't take them out until they are hard. Why am I not getting good carbonation? Is the directions wrong and I just need to let them sit longer than 2-3 days??

Since you are using PET bottles, you can safely let them carbonate longer. At room temperature, you need 60-80 psi to provide good carbonation once refrigerated. It might be worthwhile to make a cap with a bicycle valve so you can monitor one bottle. I have a Carbonator and a gas connector with a pressure gauge attached. I use it when I prime a keg mostly, but when I force carbonate a 2L bottle, I can check that as well.

Are you chilling them for a day or two after the bottles become hard to stop the fermentation, or are you pouring 75F root beer over ice?

If it is the latter that may be the problem since co2 is absorbed into solution better at lower temperatures.

ok, I guess next batch I'll let them sit longer. How long do you suggest? 5-6 days??

Also no after pulling them out of the closet I put them in the freezer for an hour then in the fridge for about a day.

I am having problems with carbonation, as well. However, my directions do advise to let the rootbeer set longer than yours do. They say to let it set at warm temps for at least 3-4 days and then set at cool (below 65 degrees) for 2 weeks for better flavor. Maybe that will help you get the fizz and flavor you desire?

Now, if only I could get the hardness in my bottles! Sigh, 6 days and not much happening in my rootbeer world....