Paranoid??

I'm a first time grower (hobbyer) and was tempted by my buddy to take some clones off his hands, 2 AK47 and 2 NYCD's, how could I resist!!! I got everything set up. Flat white walls, 400w HPS, Pro-mix soil, nutes, pots, fans, heater (little chilly in the basement) and loads of time. Following the boards awesome help I water whenever the soil is dry about an inch down, have the lights on a pulley so its fully adjustable, just the right temp 74-76, humidity is 40-50. I use Terracycle organic vermicompost (worm poop) extract once a week at about a quarter the recommended dosage and even give my plants a burst of Co2 every once and awhile. Here is the long awaited question, How come there are always 1-2 leaves that are yellow but I'm constantly seeing new beautiful growth at the top. The clones pictured are about 3 weeks old, and the spots? what about the spots. I'm constantly checking my plants like I have OCD, my buddy says chill, what does everyone else think? Thanks for all the help!

Sounds like your overwatering. If the soil is still moist at the bottom where the drain holes are you shouldln't need to water. If you had a lot of run-off you might have flushed the nutes out of your soil. Another good way to tell when to water is to check the weight of your containers. Aside from that, it looks like nitrogen defficency, not sure though.