I don't do exactly that ratio or keep it the same all of the time but I am still using the stock mix and its working really great (~700ppm). The Jacks seems to dissolve 98% of the way pretty quickly and there is always some residual. What I do now is not try to shake the hell out of it but just leave it alone for a few days, mixing it a bit here and there. Fully dissolves that way. The Cal-nit dissolves with zero issues.
i believe the numbers i quoted above get you right around 1.3ec....