Quote Originally Posted by avandesande
Muriatic acid and sulfuric acid will eat up your pipes.

Phosphoric acid is much safer to handle and for your plumbing. I would try a pool store, i think the 'ph-down' type products are phosphoric acid.
Also look in a hardware store for 'naval jelly', same thing.
Just make sure to read the label to see if there are any undesirable additives.
Good resource avandesande. Thanks to you too.