block fill prep

Muriatic acid and then rinse it out with water...It is the only way to do it...If there is even any dirt/debris in those water jackets, the block fill will NOT stick.

You can get muriatic acid at any hardware store...Just wear gloves, use it in a well ventilated area (and somewhere where you don't care if the ground changes color) and then rinse it all out real well after a few minutes