brown root tips but plants look great

today i noticed a couple of my plants have brown root tips.im growing in dwc the plamts are in week one of veg my ph is 5.8 in res and the water temp never goes above 73 usally around 69 it stays. some of the roots are in the water but the ones that have not reached the water yet are the ones with the problem. my ppm is 890 cause i used tap water changing to disstilled sunday. i didnt have any covers over the rw so some light was gettimg in i have since put covers over them. not sure if im watering enough to keep them moist i started drip one min every three hrs two days ago. looked like they were starting to droop so i stop to let them dry out a bit so the roots will grow. thanks my temps are 82-86 using co2 rh is 50-60 any help would be helpful

wait. brown? like a light brown? smell them. do they smell like dirty socks?

the biggest issue that comes with DWC is root rot i think. i lost a beautiful plant to it. and it sucks. what i ended up doing was i had a screen mesh between the mesh pots, and the water in the reservoir. all the water dripped from the hydroton balls down the roots, into the big pile of roots underneath (looks like a huge pile of spaghetti), then it drips thru and back into the water. the idea is the roots stay wet all the time, but they never sit in water. one thing i did was i got some fungus and mold killer (that works as a spray for roots) and added it to the reservoir as well.

post up some pics. DWC is hard to do but very rewarding.