Advice/Help. Leaves turning white/brown on tips

[SilverIceCat]

This is my first time growing and I was after some help or advice.
My plants are about around 5 or so weeks old, and I've noticed over the last 3 days that the tips of the leaves on the top of one of the plants and on the bottom of the other plant have started turning a brown and white color. Was wondering if anyone has any idea what is causing it

Im growing in coco coir/perlite mix with a 400w HPS light in an air cooled reflective hood. Been using coco canna A and B nutrients and around 1/4 strength and been watering then around every 2 to 3 days with plain PHed water in between nutrient waterings.

Any advice would be much appreciated.
Thank you in advanced.

[Jr83]

Looks like nutrient burn to me have u fed them before now usually plants don't need fed for the first 3 or 4 weeks so if u fed them before now just skip a feeding or keep it at a 1/4 strength if it happens again give a bit less nutes but yeah I'm pretty sure its nute burn its pretty common just don't let it get worse or you'll stunt ur plants a bit of browning on the tips is the most u went

[Jr83]

If u look at my tips on this one they turn a bit whitish yellow then brown that's nutrient burn if urs looked like this dont stress just cut the nutes back a smidge

[Canuck147]

Looks like calcium/magnesium deficiency. I say that cuz they should be a more vibrant darker colored green. I use CaliMagic by General Hydroponics - works great.
If you don't treat it, the leaves will get uglier.

[SilverIceCat]

Thank you. Ill grab some cal/mag tommorow and see how they go with that.

[D.A.A.S.69]

That looks like a deficiency to me to.
Like 147 says they should be a good bit darker.

[UrbZ]

I would agree with all of the above. Im new to this myself (1st grow) and My plant looks almost exactly the same as you. I went a little heavy on the nutes my first feed got a little tip burn but not heavy. My baby is green just like yours most likely low on nitrogen and a couple other key ingredients. A good dose of cal/mag will help substantially it has nitrogen (good sized dose) sensei by advanced nutrients is 4% nitrogen, calcium, magnesium and iron. I just got my cal/mag today im planning on doing a dose of that and seaweed with plain phed water on my next feed. I would suggest the same for you, as ive gathered info from my help thread and around the web that seems to point in the right direction with my issues.

[D.A.A.S.69]

Yeah a little tip burn ain't a bad thing.

[UrbZ]

Yeah my nute burn was so incoincidental it only got the bottom 2 leaves and only like an 8th of an inch on each tip. I myself couldn't have asked for a better result with my first feed.