Bit of a problem

[Outragedpluto]

Good evening all. Hope you all are having groovy evening So over the last few days i have noticed a little problem starting to occur. It started out looking like nute burn and now is looking more like a deficiency of some sorts. I have scoured my books and re read a lot of things and i think it may be magnesium. The way the leaf is turning brown on the edges and getting crispy and dead. Moves from the edge in. Only effecting the older leaves on the lower part of the plant. The entire top of the plant and new growth look awesome. No sign of a problem. I only use distilled water. I have only used one tea in her life. So that means i have only used CalMag once.

Please let me know what you think!!

Here are some picture of her in full.

Thank you every one for any help!! Have a great night!

 

[Outragedpluto]

Here is a little info on my grow.

What strain is it? Buddha Seeds Magnum Autoflower Fem
Is it Indica, Sativa or Hybrid? What percentages? Not sure on % but Indica/Sativa/Ruderalis
Is it in Veg or Flower stage? Autoflower 39 days old
If in Flower stage... For how long? 10 days
Indoor or outdoor?Indoor
Soil or Hydro? Soil. True Living Organic style of growing
If soil... what is in your mix? The Revs 2.1 Soil recipe i made last season
If soil... What size pot? 3 gallon finishing pot
Size of light? 400 watt HPS (MH burn out, need a new one)
Is it aircooled? yup air cooled sealed hood
Temp of Room/cab? currently 80-85 during light on and not sure about lights off. not warmer i would assume lol
RH of Room/cab? 65%
Any Pests ? nope
How often are you watering? SWICK style with distilled water
Type and strength of ferts used? none, soil will do the work for me. should only need water from here on out
Air filtered through 4 inch carbon filter

 

[capitano]

It defo looks like a magnesium deficiency. i've had the same

 

[capitano]

check you're PH as well as you may have a lock out