I just fill a pail approximately 1/3 full of CQ, add running water while swirling the sand with your hand, pour off dust & dirt carefully so as not to lose any sand. Repeat until the water runs clear.
I have a few tanks with CQ, I wish it was still available.
Eheim Pimpette #270
Eheim Pro II 2028; Classics Series -2215, 2217, 2260, 2262; Pro 2229 Wet/Dry