Apis mellifera mellifera(AMM) honey bees

[Jon]

This states that 3.2% is a good strength for your average colony which is what you get with the ratio I quoted in the post above, 7.5, 100g, 100g.

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Jon wrote:
The standard treatment is 5ml per seam irrespective if it is a double or single brood colony.
It is not necessary to separate the two boxes in a double brood colony.
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The 5 ml trickle has to be carried out for each occupied comb space in a double brood box situation. I quoted Ian Craig’s wintering method of 8 frames/brood box. Jon’s recommended procedure would have Ian’s bees underdosed by some 35mls: A potentially dangerous situation if all 14 bee spaces are occupied. In Ian’s system this is a distinct possibility.
Eric..

Eric.
If you want to follow your own calculations you are free to do so but don't encourage others to do this.

I quote here from the back of the box of 500g of Oxalic Acid Dihydrate supplied by Thorne who as you may know are a large beekeeping supply company in the UK.

Preparation: Mix 1 litre water with 1k sugar. Add 75g oxalic acid dihydrate (which contains 71.4% oxalic acid). The resulting solution will provide 3.2% oxalic acid. This should be enough to treat 25 hives.

There are far too many beekeepers who either ignore, or are unaware of current best practice with regard to Oxalic acid strengths and dosages.
Most of my colonies need about 30ml based on the number of seams. I don't think this is unusual at all for AMM but if your experience is with more prolific or hybrid types of bee you may need the full 50ml. 50ml is the recommended maximum even for a double brood box colony.
My practice (and calculations) follow all the published guidelines for mixing and applying Oxalic acid.
I prefer published research to personal calculations as the dosages have been trialled for years over many colonies.
Do some wider reading if you don't believe me. It's all online.

Gav. Surely this should be moved to an Oxalic acid thread.