It should smell kinda like fresh vegatables. Almost like alfalfa sprouts or something. If it smells like dirty or mildewy and the water is really cloudy you have a problem.
Thats likely not a good thing. Is your system light-tight? What is your res temp? Anything above 70 (65 is ideal) and you may run into issues. I've had good luck with h2o2 and SM90 for fighting algae, etc...
are you useing organic nutes,I have never used them but I would think you would get some smell from organics,I use GH nutes and my water smells fresh,if its really stinky you may have problems good luck
if they are white & healthy, no worries, keep it under 72 and they will thrive. your plant's will tell you if there is a problem long before the roots. but all sounds well