What pH are you watering with? Are you feeding it nutrients yet? What brand of soil are you using? New growth yellowing could be iron deficiency but most seedlings and clones don't need a lot of nutrients so I'm leaning toward a pH issue. Look into "pH nutrient availability" on google.
I started to put it outside it's been nice in So Cal and using a low wattage light with the three bendable arms. about 4 to 6 in. away. Leaves were on the dark side. Started to put it outside they have been lightening up.