What is wrong with her?

[Sc0tt]

At first glance I thought it was nitrogen deficiency.. the bottom leaves are still green as well as the leaves at the top so it has to be an immobile deficiency, right?

[OldManGrower]

What is your PH? I will bet it's out of wack.

[dilvish]

When the plants get pale green its typically a nitrogen deficiency and yes, likely due to PH issues or simply not enough nutrients. watering in Soil should be 6.5 PH and remember to test the water PH after you have added the nutrients to the water.

Yellowing leaves on the bottom of the plant is natural as it grows bigger and bigger. lack of seeing any doesn't mean everything is okely dokely....

[dilvish]

Nitrogen deficiency does not just start at the Bottom. Clearly the soil you bought is either old or it's not holding up to it's claim or worse, the PH of your water is not good for the plants to be able to absorb the nutrients from the soil.
Either the soil has lost it's nutrients quicker than you thought or the PH tester is not properly calibrated.

Unfortunately super soils can be great or a hassle and that's why a lot of growers opt for plain soil or coir and then add liquid nutrients. Adding them on a schedule at specific amounts means you control the whole process.

[BCOutdoorBudz]

You won't be able to darken the leaves back up in flower the plant won't take in the extra nitrogen at this point. You'll always see a bit of fading and leaves starting to die off later in flower

[dilvish]

Light stress is typically only the top of the plant but your problem appears to be all over the plant, A good rule is check with the manufacturer first regarding distance. Unfortunately cheap lights can be very problematic so hopefully its not that. Again its a nitrogen problem most likely