I'm about to replenish my supply of Hydroquione purchased from Photographers Formulatry. To purchase it locally I can shop at Adorama but they list Photographers Formulary Hydroquione as Residual Hydroquione. I cannot find Residual Hydroquione at the Photographers Formulary site and wonder if I may be getting something I need to adjust my formulae for? What is the difference between Residual Hydroquione and Hydroquione? Are adjustments in usage necessary? Any idea which way? How much?