Selected Answers

From Andres Weber of Chemical Technology Inc. on November 15, 2012:
Phosphoric acid at a low concentration is a great ...read more Phosphoric acid at a low concentration is a great way to solve this problem, too.

From Joseph Berchenko of Arcom on November 12, 2012:
     If CMU is new and there a ...read more      If CMU is new and there are no leaks or water sources, it may weather off by itself after a while.

From Glenn Summers of Conselcor Inc. on November 12, 2012:
     Yes, it may be removed, a ...read more      Yes, it may be removed, and any acidic material should be used sparingly since we don't want an acid to loosen the limestone bond to the fine aggregate. Once removed, a quality penetrating sealer will prevent it from returning.

From web stokes of DMA on November 7, 2012:
     Yes, with a mild acidic s ...read more      Yes, with a mild acidic solution. Acetic acid works well.