Johnnie's Home and Hardware Acid Magic
Acid Magic is a full strength 1-to-1 replacement for muriatic acid that has 90% fewer fumes and won't burn intact skin. Dampen the area first with water, then spray on Acid Magic. It will foam up, and then you scrub with a plastic bristle brush. Rinse with water. Let dry. Repeat if necessary. After you clean the brick, seal it with Drylok Masonry Sealer.
$19.99 - $28.99
Johnnie's Home and Hardware Zep Acidic Gel Toilet Bowl Cleaner
Clinging gel-based formula cleans with little scrubbing.