the lettuce has yellowish roots.
 

hello ron,

i notice that out of the 3 types of plants i have in my hydro system (namely, lettuce, rocket salad and basil ... all sharing one tank), the lettuce has yellowish roots.
this is my first time to encounter this. i have been doing hydro for months now. the only difference i could remember is that for more than 2 weeks now, i do not put any Chlorine in my solution. before, i make sure there are no less than 10ppm of Cl in my tank.
oh, if you are thinking that i do not change my water, well .... i do change my water. actually, my water evaporates so fast that i have to refill it every 3 to 4 days.
regards,
pzing email: freshfields@guest.sendit.se

Not sure but I wouldn't worry unless the roots turn brown and die.