Originally Posted by redfishassassian
I'm using white sugar in the mr beer plastic bottles. Temp stays in the low 70's
How much sugar per bottle? If you are adding sugar by the bottle you can have inconsistent priming. Your temps are good. Three weeks at 70 degrees if the minimum is primed correctly. Do a search on batch priming. This is a more effective method to ensure an even amount of sugar in each bottle.