As previously stated, citric ...
Published by JOSE LUIS TALAVERA, PRIVATE DESALINATION CONSULTANT
As previously stated, citric acid is a weak acid and must be used only for removing iron and manganese. It's not going to avoid calcium sulphate or silica scaling.
The problem is due to the inverse solubility of the calcium carbonate and sulphate, where the solubility decreases when the temperature increases.
Citric acid could avoid the calcium carbonate scaling if you reach the right pH ( Negative Langelier Index) but has nothing to do against Calcium Sulphate or Silica.
The solution is using the apropiate anti scalant from a recognized company like King Lee, Nalco, Genesys, etc, which have a battery of antiscalants for different scenarios.
Send the water analysis to them and they will solve your problem.