Garyj, as the water passes it draws the stock solution from the bottle,
mine mixes at 8:1 thats 8 parts water and 1 stock.
If your stock is applied at eg 16:1 you would mix up your stock at 2:1
a bit of maths is involved.
eg Mpower at 120:1 120 divide by 8 = 15
so you would mix stock in bottle at 15:1
Best to have a few, i carry half a dozen stock bottles, trying not to leave much if they
have a short shelf life.
Andrew