I have a 27,000 gallon pool with iron staining.

I have had conflicting information about how to remove the iron and keep it from returning. The pool maintenance company would like to drain and acid wash the pool, then refill it with filtered water. The pool store wants to sell me stain remover. The maintenance people say that the stains will return as soon as I shock my pool if I use the chemical from the pool store.

I would greatly appreciate any help! Thanks.