Does this look like magnesium deficiency to you?

[The123321]

I have 2 auto plants on day 15 that look like they are starting to have a little yellowing between the veins on some of the leaves. Does this look like magnesium deficiency to you?

The details on it.

• The plants are mephisto sour crack on day 15 in 50% soil 40% perlite 10% biochar in 3 gallon fabric pots on there.
  
  
• I have the 240w kingbrite quantum board led 3500k with 660nm red on like 70% power at like 40" from the top of the plants in the tent with like 77 - 79f with 50 - 55% rh on there.
  
  
• I water with tap water with ph 6.0 - 7.0 that I use ascorbic acid vitamin c powder to remove the chlorine or chloramine in it. I have done a few waterings with coconut water and 1 watering with aloe in it.
  
  
• The nutrients are biotabs organic dry amendments with 2 biotabs per pot with startrex mycotrex and silicium flash in it. I follow the just add tap water guide from biotabs for it.

Do you think that is magnesium deficiency or what? I want to find out if people think it is magnesium as I would then plan to put some epsom salt in the water next time I water it for it on there.

 

[Carcass]

My Gelat.og auto had something similar going on- it was just hungry-I had to feed it "big plant" quantities
when it was only 3 weeks old...but that cured it.
I use MegaCrop so it was easy- not sure what you'd do in an organic situation... but my point is ,it looks hungry...

 

[The123321]

Thanks.