Advice please

This is my three week old baby. They were under fluorescent until Friday when I put them under my 600w HPS on a 18/6 schedule. I have the the light about two feet away from the tops of the plants. They're in a 4x4 tent that stays at 84 degrees when lights on and about 60 when lights off. I water daily without any nuets. They seem to dry out quick which is why I'm watering daily. They're in 16 oz solo cups obviously and I'm using Dr. Earth for my medium. I have a small fan blowing on them while the lights are on and not when the lights go off. These yellow spots started showing up and I have no idea why. All the research I've done for yellow spots, the plants are always way more mature and the cause is usually nuet burn. Since I've not given them any nuets, that cant be the case. I also don't see any spider mites dwelling underneath the leaves either. I'm using tap water that I let sit out and I'm not sure the pH, but I live in the city and all the research I've done says the pH of city water is usually fine but let the water sit so the chlorine can evaporate. Is this something to worry about? What can I do to fix it? I am seeing more growth daily so I know the plant is still growing. How concerned should I be? Thanks for any and all advice!!

U gotta get bigger pots they are seriously root bound that's why it's drying up so quick it's like if u were out in the sun all day and all u get to drink is a Dixie cup of water

Hiya M8,

You need to transplant them into bigger containers. They are ready to stretch out and grow, not to mention with the upgrade in lighting, they need a bigger playground.
Feed them plain water( distilled if you can) after you transplant them and see how they react, then if they show a positive responce, they will be ready for a 1/4 strength or so nutrient feeding next go around.

Peace and Great Grows

Asmallvoice

Thanks Guys!!!! I'm going to transplant right now!!