Tom Barr in "Want more accuracy? Want daily PMDD style EI dosing?" said:(or you can use a mix of Fe DTPA + CMS+B, at 1:4 ratio and mix 1 table spoon to 1 liter of DI water, add HCL or Excel to prevent fungus etc)
In what ratio is Excel used as a substitute for HCl? I've seen Excel has a limited shelf life, so how much is needed to be used in 1 L of liquid ferts, or is it the same amount?