Potassium and/or magnesium problem? Deficiency or abundance?

So... having some sort of nute issue again. The lower leaves are curling down, looking papery. The upper leaves look like they ahve some burn on the outsides and are curling up. I just watered with straight pH 6 tap water to try to flush out whatever's up. Once that's done... I can't seem to nail down whether this is a magnesium or potassium problem (seems excess K can lock out Mg, but i'm not sure thats whats happening). They're in soil, under CFL, its Tangerine Dream.

Any ideas?

Looks like a mag def to me. Either give them some cal/mag or epson salts.

P & K are best absorbed at around PH6.5 and if there was too much nutes in the soil it would've locked out in acidity therefore I would have flushed at PH 7.0. Did u check the run off? What week are they in? What's the NPK ratio of ur nutes ?

its a calcium difficiency mate, notice its comming in the the zigzag edges in.....i would double read the problem forums and find out what your doing wrong which depends on your soil, to much watering etc...u can also but MICRO nutrients like CAlCIUM and water feed with that ..its a powder form u just add water, but please post more of your growin details.

lokks over-watered too. give us the dirty details