Home Brew Bulk Priming With a 20 Litre Cube

Bulk priming is mixing priming sugar into the whole brew  in a separate container just prior to bottling.

Bulk priming vs putting a measure of sugar into each bottle is debated by some home brewers:

Advantage of bulk priming :

• Even amount of sugar in the brew regardless of bottle size
• You can prime with dextrose or malt which is too messy and fizzy for spooning into individual bottles.
• Quicker? Thats debatable..Less fiddly, that's for sure.
• Get all the beer off the yeast cake in one go so your last bottles are not "scraping the bottom of the barrel".

Disadvantages:

• Risk of aerating the beer.
• Risk of contaminating beer.

The key idea that I came up with was to:
bottom fill the 20 litre cube right to the top so that:

• Beer is not aerated 
• Close the cap and tap on the cube once its full and it can be gently inverted to ensure good sugar mixing.
• Can be moved to a convenient bottling location without risking stirring up the yeast.
• Only the inside of your transfer tube need be sanitized.
• Cubes are easy to sanitize by shaking a bit of sanitizer around inside it.

Notes: 

• I put 180 grams of dextrose(glucose) boiled in 500ml of water into the cube first.
• Make sure you brew a little over 20 litres of beer. 
• I used a "food grade" water hose from a boat equipment company (Whitworths in Australia)
• Tissue over airlock hole to reduce dust sucking in. 
• The tap on the cube was slightly rotated up while filling and it didn't seem to affect the seal.

P. S - I now think 180g of dextrose is too much. I haven't tested it but 100g would be better. Will update how it turns out later.