Sodium fluorosilicate solubility in acid (such as phosphoric acid) is very small, a certain temperature at a certain concentration of acid dissolved sodium fluorosilicate is actually a balance, if you want more than three ways to dissolve:
1) Maintain the acid concentration in the maximum dissolution zone of sodium fluorosilicate;
2) increase the temperature of the acid;
3) The same ion effect as if the addition of iron ions could promote the dissolution of sodium fluorosilicate.
This method is for reference only. The specific implementation method is based on the technician's operation.