I'm with you. Roughly 100 TDS for 6gh. Not all the powder dissolves at once, so even after what I see dissolves, I let it site some and then mix some more. For myself I wait between 1/2 hr and 1 hr.
I try to keep my TDS swing within 100 for neos and 40 for my cards. I'm a bit more harsh on them than average people I think, however I really try to develop hardy strains.