I just checked your diary. The yellowing of the seedling leaves is of no concern at this age, often the first few sets of leaves can be "funny" as the plant establishes itself and I would definitely not feed or worry about the leaves at this age of your seedlings, they will work themselves out and get going soon enough.
However, growing autos and photoperiod plants in the same tent is going to pose problems, your photoperiod plants will not flower at 18/6 and your autos will not perform very well at 12/12.
When it comes to tent growing, it is all autos or all photoperiod plants and never mix the two, otherwise one is going to lose out, sorry to say.