No worries about rot at this stage of growth. That is only an issue for very dense buds late in flower. If your temp is in the 70'sF, then your humidity is right where it needs to be.
For veg stage, keep it in the green as best you can. Too dry at this point puts you in the red and plants pores in the leaves close up and growth is stunted. I believe that is the problem I had on my last grow. Sorry if I've posted this already. I forget who I've replied to. So anyway, don't be running that dehumidifier at this point. Do remember that a dehumidifier will also add heat to the room.