whoawhoaanswered grow question 5 years ago Hi! For what I see on your diary, you normally would need higher levels of Cal-Mag supplement, like 1.5~1ml/L for the entire grow. From pics it seems that there are a couple of problems there (leaves curling up, some of them are kind of glossy and seems to be hard/plasticky).
I'd first increase Cal-Mag supplement to at least 1ml/L.
If you're in doubt if it's Mag deficiency, make an epsom salt solution and spray under the foliage, should address it quicker than root feeding.
Check roots to see if they're dark or slimy, if it is, probably starting to rot, increase aeration and make their water slighty acidic (pH 5.6~5.8)
It's good to remember that in hydro, water pH is slightly increased due aeration, so make sure that you test reservoir pH with bubbles on, or at least with a good stir.
EC is kind of low for week 4... What is your plain water EC? I'd increase nutrient dosages to 0.66~1ml/L. Start on lower end and increase nutrients if you feel well.
Also, those brown patches could be from pH fluctuation, that could lock your nutrient uptake, so give them new water with pH 5.7~5.9 for now. On hydro water pH changes from time to time, so try to play with their pH from 6.0 to 5.6 during the week, at least until she's flowering, so they can absorb all of the macro/micro nutrients correctly.
For last, it is pretty rare, but only for sake of knowing it, check your water's Iron ratios... If you have lots of Iron or if your water comes from a well or maybe rain water, you could have some type of Iron excess.
I'm not an experienced grower, everything here is from my little knowledge and some things that I read.
Hope everything turns ok for your grow, cheers!