Is this a nute deficiency?

[Percula]

Hi All-
New grower here. Trying to determine if I have something to worry about.
Strain is Mac n Jack
Coco/Perlite
FF Grow Big at 1/4 recommended strength for the first 2 weeks, now up to 1/2 strength. I've added Microbe Brew occasionally, but I don't know if it does anything in Coco. I' have CalMag but I use tap water so...
Temp is steady at 78. RH is 60.
I see purple stems and yellow tips. Phosphate def? Magnesium def?
Any Info will be greatly appreciated!

 

[2Bad]

How close is your light

 

[Percula]

I'm using 2 Sylvania 20 watt plant bulbs (My HLG is on the way) 14" above.

 

[Gmix]

Strange light colour.
Apart from that your getting another anyways
All I see is a little tip burn where they had enough food for a bit how old that is only you know.

Might be best to only water next time & cut back on the nutes

 

[GreenGalaxyFarm]

would stick with 1/2 strength nutes using weak light, when you proper light come gradual increase
how often are you feeding

I'm using 2 Sylvania 20 watt plant bulbs (My HLG is on the way) 14" above.

 

[Percula]

I'm feeding once per week at 1/2 strength. The light is arriving today. Question about the photoperiod: They have been under 24 hour light. If I cut back to 18/6, would that induce flowering or is it the 12 hour darkness that does that?

 

[Cirroji]

I'm feeding once per week at 1/2 strength. The light is arriving today. Question about the photoperiod: They have been under 24 hour light. If I cut back to 18/6, would that induce flowering or is it the 12 hour darkness that does that?

i run my photos at 24hr in veg, 18/6 just saves me some electricity.

plants look fine, the yellowing of the tips is very slight nute burn (aka more than needed so no def)

 

[GreenGalaxyFarm]

I'm feeding once per week at 1/2 strength. The light is arriving today. Question about the photoperiod: They have been under 24 hour light. If I cut back to 18/6, would that induce flowering or is it the 12 hour darkness that does that?

generally yes 12/12 will induce flowering, some strain require less than that
or if you are growing sativa dominant you may wish to lower flowering time by reducing lights on