How many balling salts?

[SeanT]

I thought there were 3 but I now see 4.

[gearbox]

There are 4, if I understand the questions correctly

1. Calcium chloride (CaCl2.2H2O)
2. Magnesium Chloride (MgCl2.6H2O)
3. Magnesium Sulphate (MgSO4.7H2O)
4. Sodium bicarbonate (NaHCO3)

but only 3 solutions. You use a balanced mix of the two mag salts, you can use this calculator to assist with the quantities

http://www.faunamarin.de/eng/manual_balling-methode.php