I used Prime Dose recently to increase the carbonation in a batch of Irish Red Ale. I had carbonated it in the bottles, but didn't get the level of carbonation I usually get. It has been 4 weeks, and it worked to get the carbonation level up to what I wanted. Like others though, the capsules do not dissolve. It is gross and I will have to filter out each bottle as I drink them. I notice that you cannot find this product anymore. Northern Brewer (where I bought mine a few weeks ago) and Midwest Beer Supply no longer carry it on their web site. I guess the price and problems such as the capsule not dissolving led to the product demise.