I'm stumped...random leaf abnormalities

Been searching to try to find a solution for this problem, but I can't come up with a definitive cause or solution.

Background:
Nirvana PPP fem, 3 wks in
My own "custom blend" soil ~75% MG seed starter (.05/.05/.05) with ~25% general purpose potting soil (.1/.08/.06)
CFL - currently 3x 23w 5000k overhead
homemade box 3x3x4 approx.
direct airflow on the plant...temps are 75-80
water with filtered h20 allowed to sit at room temp for 24hrs

Germed well, tried to start it in a large pot to avoid transplanting, but couldn't keep sufficient moisture for the seedling without drenching the pot. So it was transplanted into a small pot. 1st set of leaves got screwed...very little growth after transplant to small pot. New growth starting coming in at a normal rate tho
Here it is after a few days in the small pot


After a few more days still looking good...slight curl in leaf tips...


Noticed some roots poking thru the bottom and transplanted into the large pot. After 2-3 days noticed some brown spots on lower leaves. The plant was doing well overall (consistent growth, new growth looked vibrant, majority of leaves were upright). The spots started in the center of leaves and did not seem to involve the tips until after several days. After some time now, more leaves are involved, moving upward on the plant...

This is a current picture, but this is what the early stages of the brown spots looks like


Seems to originate at the central vein. The spots will continue to grow in area over the leaf day by day. This is the first leaf I noticed with the spots about 1 week later:


The yellowing at the tip is a late symptom. This leaf is now very brittle and will break off...like this one did when I brushed up against it


New growth is unaffected. The top half of the plant looks very well. But the problem is definitely traveling upward. The central leaf of any given cluster seems to be the first to be affected, but as you can see above, neighboring leaves soon follow.

I have investigated as much as I can. Looked at all the pics of deficiencies and whatnot. Some of the leaves look to be twisting so I have considered a pH related issue. My best guess based on appearance is Phos def secondary to an elevated pH.

I also think I made a poor choice on soil. I figured the seed starter soil would allow for good aeration, but it turns out the top 3-4" of soil are drying out before the rest, so the roots higher in the pot are becoming dry. This has forced me to do some erratic watering (using small amounts to just moisten the top few inches). These symptoms don't appear to be due to lack of moisture however.

I do use some feed, but at very low concentrations. Neptune's fish/seaweed 2-3-1 at about 3-4 mL/Liter. I only have a soil pH meter (which I'm not sure I trust) which indicates soil is 6.5-6.7.

I have some ideas, but not sure which to address. My biggest reason for confusion is that the plant continues to grow at a normal rate, but lower leaves are biting the dust. This is why I suspect the top few inches of soil drying up as a partial cause. Looking for some ideas if this is a deficiency or if I just need to address the moisture not being evenly distributed in the soil. Thanks for any input!!

Here's a decent shot of the whole plant. Tops half is thriving but I can't ignore whats going on downstairs

Well I never got any responses obviously lol. No offense taken, but I'll give you assholes another chance to help out haha. I went forward with the grow changing little things here and there to try to rule out causes. Tried reducing the feed concentration, watered with just plain water with no feed, tried some superthrive (very low conc, one drop/gal). At times it seemed the problem had stopped or slowed but newer leaves keep appearing with brown spots. They will eventually look like the really ugly ones below. The most curious thing is the plant has grown well otherwise. Its a little short, but very bushy. Why are just random fans involved. Most deficiencies will usually consume the entire plant if not corrected. I initially suspected my poor soil choice caused some root damage by drying up un-evenly. Perhaps that is the cause. I went away for 3 days and came back to some really crispy leaves. 3 days is my usual watering interval but the plant is clearly demanding more...soil was bone dry when I got back. Its not getting any taller but side growth is bursting out like crazy.

Its more of a curiosity now. The plant obviously has some stress so it prob won't produce substantially (not that a cfl grow would anyway). I'd just like to hear some ideas or at the very least document my grow problems for anyone who comes along in the future with similar issues. Let's see what happens I guess...just switched to 12/12 yesterday. Here's some pics..

Some leaves are very ugly




Some early signs on some of the upper leaves


But the overall plant is pretty good

add some epsom salt 1/2 tsps per gal for a few waterings

i'm not sure but it looks like a fungus. i'd spray with a fungicide like Senerade it u can get it.