Guess the Deficiency! (w/pics)

Hi good people of RIU

need some help identifying a problem that started about 4-5 days ago.

Growing Barney's Farm LSD, in soil (a local grow shop recipe, should be similar to BioBizz Light-Mix). end of week 4 of veg, 5 plants are in 10L AirPots. feeding them in every watering (every ~5 days): all BioBizz: 2ml/l BioGrow, 2ml/l BioHeaven and 2ml/l Alg-A-Mic.
all 5 plants are under the exact same conditions, but 2 of them started showing signs of what looks to me like either N or Mg deficiency. bottom fan leaves are almost bleached, with purple marks on the stems. and it also appears like the new growth on these 2 plants is much lighter in color. so i cant quite understand what's going on... am i underfeeding them (or overfeeding, god forbid?). if this is Mg deficiency, is Alg-A-Mic enough, or do i need to add some CalMag, or Epsom Salt (not sure i can get CalMag where i live)

Water: PH: 6.8 PPM: 800

Run off water: PH: 6.7 PPM 430

attaching some pics...
PLEASE HELP!

thanks

I've got the felling you're right about N deficiency. think maybe your ph is a bit high, but I'm not a soil man.

Looks more like overwatering than a simple N deficiency to me. Notice how the leaves are a little cupped downward?

Are you watering them all at the same time? If so, you are overwatering the ones that are a little less vigorous (and now even less vigorous because of the sogginess!). It's an issue that can snowball really quickly..

SpicySativa said:

Looks more like overwatering than a simple N deficiency to me. Notice how the leaves are a little cupped downward?

Are you watering them all at the same time? If so, you are overwatering the ones that are a little less vigorous (and now even less vigorous because of the sogginess!). It's an issue that can snowball really quickly..

Click to expand...

Thanks spicy, can overwatering cause bleaching of the lower leaves?
Anything I should do, or just wait?

SpicySativa said:

Looks more like overwatering than a simple N deficiency to me. Notice how the leaves are a little cupped downward?

Are you watering them all at the same time? If so, you are overwatering the ones that are a little less vigorous (and now even less vigorous because of the sogginess!). It's an issue that can snowball really quickly..

Click to expand...

Watering them all at the same time, b.t.w. and these pics were taken a few hours after watering, not sure if it makes any difference...

Thanks again for your help

Yep, looks like N!!

2xM said:

Yep, looks like N!!

Click to expand...

Thanks 2xM, it does have all the symptoms of N def.
it actually started when the soil was almost dry, so I don't think I'm overwatering. And also, these AirPots have excellent drainage and aeration, so the soil dries relatively quick.
fed them some biogrow yesterday, so we'll see what happens.

These leaves will never go back to green though, right?

Probably is the N then. They sometimes do that minor droop right after a big drink, so that's probably what Im seeing.

Increase your nutes a bit. Add some cal mag too, it has some iron in it which should help out