Older leaves and browning and crisping.

A few weeks ago I bought a cheap-o soil PH meter and realized my PH was way low. I flushed with some PH up and thought I solved my problems. My PH meter now read around 6.3 (not sure how accurate this thing is). I tried to test the runoff, and it looked like about 6.0. I am still trying to get it up a little higher, but PH up seems to have stopped working.

The baby in question is about a month old, but kinda small because it started in such crap soil. The only nutes were very low strength organic. I had problems with the lower leaves yellowing before the flush, but afterward that is gone.

Now the lower leaves are spotting with brown. No signs of yellow like before, just turns from a nice green color, to brown. Rub it between your fingers and it crumbles away. It is mainly affecting the older leaves, and seems to be moving from the tip towards the node of each leaf (doesn't necessarily start at the very tip like nute burn, but the front half of the leaf is the first to go). If I use my imagination, the brown color almost looks purple, but not really. Maybe a P deficiency? Some of the newer leaves have some small random brown spots, but nothing is progressing up there.

Also, before I did the flush, I had purple stems. Like almost blood red. After the flush, the main stem has returned to green, but the main stem of each leaf is still slightly purple (they start green, but slowly turn purple). Growth seems slow.

Using CFLs, organic soil, neptunes harvest sesweed, pots are smallish, temps are highish. Is this still a PH problem? Or should I step up the nutes?

sounds like a ph problem

whats the ph when you first put it in your soil?
you should be more concerned about getting this PH to optimum rather than the runoff

do your leaves look like this?

Not really. That picture seems very uniform. This is more random splotches, and its not a rusty color. It is a dark brown, almost darker than the healthy part of the leaf. Like I said, it looks almost like a dark purple color if you use you imagination and it is under the blue light spectrum.