you might be able to find the salts/minerals ready made online ie.. ebay, amazon etc.. but the salts/minerals are quite easy to buy separate.
100% = non-iodised salt 3.5g/l, calcium chloride 0.1g/l, potassium chloride 0.05g/l, bicarbonate of soda 0.2g/l, magnesium sulphate 0.2g/l.