What's wrong with these fan leaves?

I need some help diagnosing these fan leaves. The first two sets are affected and the third set is starting to take a turn for the worse.

Plant: 23" tall Mexican bag seed sativa in an 18oz. party cup. It's about nine weeks old and 13 days into flower (started on Jan. 9) and is a growing learning experience before I plant good strains. The roots looked good the last time I looked at them a few days ago.

Soil: MG seed starting mix, 5-1-5. It's been in the soil for about 5-6 weeks so the nutes should be gone.

Nutes: I was using Botanicare grape Sweet and Hydroplex (0-10-6) at 5ml/g while the soil still had N in it. The last feeding was Humboldt Oneness (5-9-4) at 5ml/g and Brer Rabbit blackstrap at 1tbsp/g. I also gave it some EarthJuice MicroBlast about a week ago.

Water: I've been using spring water and pH'ing it to 7 after adding the nutes (letting the Oneness sit for at least 24 hours to buffer itself) and only water when the cup feels light, allowing for wet/dry periods. It works out to about 8oz. of water every other morning with a feeding every second or third watering.

Lighting: Currently under 78w of 2700k cfl in a room with 434w of 2700k cfl. It'll get more light after I harvest my WW in a week or so and then I'll be getting a 400w hps in about a month.

Environmental: Temps are generally low 60s to mid 80s and humidity was around 60 but now 40-50.

That's all the info I can think of right now. Please ask if there's anything else you need to know.

really? its 23'' and its still in a 16oz party cup? are you in a competition or can you transplant it? I would transplant man

I have a Cali HAsh PLant that has been vegging for a few months. she drops a random leaf or two and they die off the same way. she needs a flush and a shot of nutes. you girl is probably root bound aswell. you should transplant her.

Thanks for the replies, guys.

I know I let it get N deficient but what's up with the green spots on the margins? I assume the brown is just completely dead material.

I might transplant into a 1g. From what I've read the only real difference is how often you have to water. My tent's 2.5'x3.5'x5' so I'm trying to find a system for a decent perpetual grow with 5-6 different strains. 1g pots will allow me to cram 24 in or comfortably fit 18. I figure that if I can get a party cup grow all the way to harvest I should be able to do the 1g without too much of an issue. I should probably also mention that these were the first seeds I germinated and I guess technically still in my first grow.