Firstly stop watering every day. Use the pick up method it never fails. Pick up the pot and its heavy its fine, light its time to water. Let it dry out some between waterings. The plant actually likes that alot it allows more oxygen to get to the roots that the water displaces. Ive got 2 grows going. One tent with photoperiod plants, the other with autos. Growing Think Different, Wappa Autos and Fruit Auto. There 2 weeks old Ive watered once. The big tent with my OG Kush in it. I water maybe 2x a week sometimes 3 but thats it. There 30 inches tall as well.
Id suggest at 30 days of growing you add some nutes. Basically you have watered out all of the nutes in the soil and the plant has consumed them. Start off with 40% 50% recommended amount and only nute once a week.
What kind of soil are you using?
Over all the plants do not look that bad. The yellowing seems to be nearer the bottom. The plants have a overall droopy sad look. Looks like over watering.
I do know that as you run out of nutes in your soil you will eventually see a yellowing of the leaves...its basically cannabilizing itself to stay alive.