Alex - the easiest and a most beneficial way to alkalize especially for afibbers is to make the homemade version of Waller Water... aka WW.... which gives you the ion of magnesium bicarbonate which is so beneficial for the heart and other tissues.
You live in Australia and I'm sure that they sell Unique Water there which is also the magnesium bicarbonate water known to provide so many health benefits as a result of the alkalinity plus you get that very useful form of magnesium.
The only water I drink is my well water to which I add the WW concentrate and I also drink some of the plain WW concentrate just to make sure I have a tissue pH that is consistently alkaline so I don't waste important stored minerals (especially from bones). Easy and economical.
Jackie