Does EDTA release the calcium it chelated from hard water back, if we reduce the pH to 4?

EDTA doesn't chelate calcium at pH 4 correct?

If we add 0.1% tetrasodium EDTA to hard water, the pH would be around 10 and it chelates all calcium. If we then reduce the pH to 4, will it releases the calcium that it had chelated back to water?

The same question for magnesium. 

Comments

  • @Abdullah Generally speaking, above a pH of 10, you'll have EDTA with 4 carboxylic groups available to form the complex with metallic ions, while at a pH of 4, you'll have only 2 (still being able to form a stable complex with divalent ions, but less with ions of higher oxidation state). 
  • ketchito said:
    @Abdullah Generally speaking, above a pH of 10, you'll have EDTA with 4 carboxylic groups available to form the complex with metallic ions, while at a pH of 4, you'll have only 2 (still being able to form a stable complex with divalent ions, but less with ions of higher oxidation state). 
    Thanks
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