Nitrogen Deficiency? What is wrong with my plant?

Hello all,
This is my first post. I'm a newbie grower, just started fairly recently and I'm pretty sure I have compiled more knowledge researching how to grow marijuana in that time than I have from finishing my BS in chemistry... so i'm quite into this... and high on crack (green crack, that is). Bear with me.

So far my grow has been going great overall. I am noticing one problem at the moment however that I'm not sure how to identify. The leaves are yellowing on the serrated tips across the edges, and on the very tip of each leaf I am noticing a lot are browning and getting crispy. I'm convinced it's a nitrogen deficiency just by looking at photos online, but i'm hesitant to up my N concentration in my nutrient solution as this plant is still looking quite young (it's 5 fingered leaves are just coming in... though it looks like it might be a second set of 3 fingered leaves, idk).

I have pictures of a few of the worse leafs attached, what do you think? Nitrogen deficiency or something else? I am growing in coco coir with CFLs (blue spectrum right now) using general hydroponics flora series and cali-magic. Watering about every other day, and every other watering is PLAIN water w/out nutes, the rest of the waterings have nutes as per concentration on nutrient solution guide I am using as reference. I have my nutrient schedule attached as a photo which I got from another grow guide (values of nutrient solution added are per US gallon). I also pH my water with pH down as close as I can get to 5.7-6.2 (coco coir's recommended pH), though this could be a tad off as I am using pH strips which are less accurate than pens, but they work.

Right now I am using "week 1"'s nutrient schedule (see photo). My plant is still technically in the seedling stage so even though it's been above soil for about 2 weeks now I have still been using week 1's nutrient concentrations. What I noticed is that the flora grow is much lower for week 1 (@ 1/8 tsp per gal) than week 2 (@ 1/2 tsp per gal). Should I up the go up to 1/2 tsp per gallon of the flora grow (which contains most of the Nitrogen)?

Nitrogen deficiency? Something else? Any help is greatly appreciated!

Other info:
-CFL total wattage = 50 W (good enough for this small of a plant right now). Held about 2 inches away from plant.
-Humidity is kept around 40-55 usually. Occasionally it will dip down to 35 or so, nothing lower than 30 ever and I am getting much better at being able to control this with my cheap little humidifier.
-I have aeration via a small fan inside the box and an air filter which i have acting as an air outtake bc it occasionally gets too hot in there.
-Temperature kept (or tried) from 70-80 F, but was difficult to keep under 80 prior to adding air outtake (would never go above 85 I'd say)
-I am not monitoring EC, I have yet to look into how to do so
-This is bag seed. However, the seed was hardy af, plenty mature, and came from a bag of daaaaank buds. I was so suprised when I found it.
I plan to get more seeds eventually and set up like a sea of green or something similar once I find a dank female or two, cuz i'm poor and ganja's expensive.

A little extra input I forgot. I've read a good indicator of nitrogen deficiency is purple-ish stems. The main stem coming from the soil is definitely purple, and I can see it is also a little purple on the stems leading to the 3 fingered leaves. I don't know if having purple stems is normal or not (bc it is just a seedling still). It's been purple since it sprouted, from what I remember, and I feel like it's getting slightly more green as time goes on, but hardly. Are purple stems normal in seedling phase? Another indication of nitrogen deficiency?

It looks like possible nute burn mate. Nitrogen deficiency usually yellows the whole leaf before it starts to die off. Seems it's been a little while since this started so it's hard to tell for sure (necrosis is well set in on the tips). I'd back off to 1/2 strength on the nutes. Don't give too much this early because if you really fry it with nutes, it may never recover or just be a bitch of a thing its whole life.

Introduce nutes slowly so you can see how it reacts. I started feeding mine at about the same time as yours and full strength week 1 with FloraDuo 2 part was way too strong for them.

Nute burn from possibly watering too oftenly.

Thanks! So sounds like i'm actually using too much. Good thing I checked before adding more, I will try lowering the nute concentrations to half.
Should I also half the concentration of my cali magic (cal-mag)? I know growing in coco you generally need to feed excess Ca and Mg so would halving the cal-mag concentration damage the plant at all? Or should I keep the concentration of that where it was?

The amount used depends on your water quality I believe. I add calmag until I get 150-200ppm then add my nutes. Are you using tap water? Very difficult to say not knowing what the ec readings are. I would halve everything mate and work up from there. It could be the combo of calmag + nutes causing the burn if your base water is hard/shitty quality.

Is your coco buffered with calmag? If it is and you're on tap water, chances are it already has enough ca/mg and you're better off using the rest of the available ppm's for nute goodness. Sweeet nutes, sweeeeet. Mmmmmm :homer drool: lol

Lol. I am using tap water, and from the mid-west where I am it tends to be harder with a lot of calcium and magnesium dissolved in it (just looked that up). I am not too familiar with EC meters, but I know the way they work is by measuring the electrical current created by the ions and salts dissolved in solution. And if they give off readings in ppm and the desired ppm cal/mag for coco (which what I am using is not buffered) is out there on the internet, couldn't you just calculate the amount needed in your water by the concentration in the cal-mag, your water, and the desired ppm you find? Idk, i'm high, that was kind of a tangent idea lol.

But should I stop using tap water? Is it better to start from Distilled? (As well as halving it at this point)

Yo man, long time grower and coco grower here and your doing a few things wrong.

First off your working on your diagnosis from the wrong angle. If you are using a bottled nutrient name brand then you dont just have N deficiency or any other deficiency. The bottled nutes are well balanced, have everything the plant needs, and if you are using them properly any deficiency you encounter will be a symptom of another problem. Something like, bugs are eating my roots so now my plant looks like it has a deficiency because it now has no roots. The exception to that is Mg in coco, coco bricks absorb Mg until it is "full', after that then it works like normal, to counteract that use high amounts of Mg early in new coco or just soak new coco in Mg treated water. Once this is done, there is no need to add any additional Mg.

Tap water is ok, depending. Every area is different and it depends on where they get your water from. It can be too hard or carry pythium (root rot) spores in your tap sometimes. You only need RO if you have excessively hard tap water, or if you suspect it as a source for pythium.... however there are other ways to deal with pythium that are less expensive than RO and less labor intensive than buying distilled water. Many people think RO is used to get ride of Chlorine, this is false, chlorine in small doses has no effect on your plants. (in fact one of my secret cures to pythium is adding bleach at 0.3 tsp/gallon, keep that one under your hat for when you need it, it will save your life)

As far as watering and feeding goes. In coco, you should give them nutrient, every single time you water, no exceptions. Early veg water at like 1/4 strength, veg plants dont need much. Do you have a ppm or ec meter? If not get one. Also dont water everyother day, that could lead to overwatering and root rot. Instead let your coco dry out as much as possible between waterings, it will discourage pythium an encourage roots to stretch grow for more water.

Growing is all about your roots man, More roots, more fruits, take care of those babies and keep an eye on them. Also another piece of advice, look in running a dead rez instead of using beneficial. Think of hydro/coco as a sterile lab experiment that you control all aspects off its environment.

Update:
Thanks for all the info everyone. I'm still having a bit of issues, but I think I have figured out the problem once and for all. Over the last few days I've noticed the lower leaves getting worse and worse and my embryonic leaves are totally yellow now. Thing is, none of this is happening on the top leaves (which are coming in oddly mutated on one side..?) but look perfectly healthy and green. I've found out (I think) that it's a potassium deficiency from more research and the knowledge that it's mobile (bc only bottom leaves are yellowing). But I've found that 99% of the time an actual "deficiency" is not normally the problem with potassium deficiency, if your fertilizing. The problem is actually due to the abundance of either calcium or nitrogen in the coco, which (If there is an abundance) can block out the plants ability to uptake potassium. I have halved my nutrient solution and I've also switched to using distilled water out of fear of my cities tap water qualities.

A lot of people say tap water has nutrients the plant likes and it does but without expensive instrumentation you can't really know the exact amounts of nutrients. You may be able to get a rough estimate online from a study done on your cities water but the error is usually significant. I found out however, from google searching my water quality that my tap water does have a higher concentration of calcium then elsewhere in the states. That worries me that maybe tap water could be further adding to this problem, so I switched. I get distilled for like a buck a gallon down the street. The only downside with distilled water i've found so far is that pHing it is not easy. I added the most miniscule amount of pH down to my first nute solution I made (smaller than the amount I would add to tap water), checked my pH, and it was below 4. I was like WHAT in the F**** ing F**%.?! HOW?!
Ended up finding that if anything, even at like 1/2 nutes in distilled water, you will probably need to pH up for once. The added minerals in tap water act as a good buffer to the pH down, making it a little more resistant to dropping pH than pure(ish) water like distilled. A lot more resistant than you think.

Hopefully my first grow will bounce back for me after this