If wanting to prime a brew in one go, or batch priming as it is often called, then you need to transfer the brew once it has finished fermenting into a second clean vessel and leave all the sediment behind. You can then add all the sugar for priming to that vessel and mix in and leave until it has fully dissolved, each bottle can then be filled and already has the priming sugar mixed into it. The other way is to add priming sugar to each bottle, priming drops are very popular for doing this as they are much easier to add to each bottle rather than loose sugar:
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