[BartexooC]

Hello everybody! I have to make an interesting fertilizer for plants in Horticulture study. So I have to make citric iron (II) - C12H10Fe3O14 with iron (II) (22 %) and 3,5 pH (about 5 litre of it).
I can choose 3 components -
-  FeSO 4 - ferrous sulphate
and
- C6H8O7 - citric acid -
or
- C6H6Na2O7 - disodium citrate
I have everything to do it - alcohol, acid, dishes, everything to make it in higher temperature.
If i would like make lower than 3,5 pH I have to add more citric acid or disodium citrate? 
Thank you,

[AWK]

https://patents.google.com/patent/US3091626A/en

[BartexooC]

https://patents.google.com/patent/US3091626A/en

Thank you very much for your help, sir.
This topic can be closed.