Arobskittle
Bluelighter
I use a blue spectrum ~64,000k T5 bulb for vegetation; it's cheap and stays cool. If you want to use the same for flower, switch it up to the red spectrum bulbs ~27,000k. They should work, but as already stated you will get a much smaller yield without HPS. An advantage to using flor/cfl instead of HPS, is HEAT; you won't have nearly as much.
Yep, I am going to take a wild guess and say it looks like a typical nitrogen deficiency. Definitely a deficiency of some sort though.
N def starts in the lower leaves because the plant prioritizes the new growth to keep chlorophyll, and moves chlorophyll from older growth to support the new growth. im gonna say its not N def.