Phosphorus? CalMg? Nute burn?

[MFStank_Nugget2000]

Day 13 - Fast buds blackberry auto inside a 3x3 tent with carbon filter and oscillating fan.
Light: Mars Hydro TSW2000 running at 25%
Average temp: 78 degrees
Average humidity: 51%
Filled the bottom 2/3’s of the 5 gal pot with Happy Frog soil mixed with living soil. The top 1/3 of 5 gallon pot is only Happy Frog soil.
Feeding with rainwater which has a PH of 6.8 and PPM of 9.

I’ve been looking at the sick plant pictures thread and the closest deficiencies I saw were phosphorus, magnesium and calcium. Not sure which one it could be. Also thinking it could be nutrient burn from mixing the living soil too close to the top? Any advice or recommendations would be greatly appreciated! Thanks.

 

[Arthur]

Your under led. Cal/mg isn't an option, its mandatory. This is a calcium deficiency. Get some cal/mg and get her fed.

 

[MFStank_Nugget2000]

Your under led. Cal/mg isn't an option, its mandatory. This is a calcium deficiency. Get some cal/mg and get her fed.

Thank you!

 

[Waira]

-- What TLO soil is this, a bagged "water only" type?
With soils, it's pretty much a must to check it's pH; they are notorious for being off, badly acidic sometimes though OF is more likely to be so than HF... Ditto for the TLO, just to be sure...
You'll need to get a soil pH probe for that, not a cheapo unit either, they suck... Accurate 8 (Control Wizard) is a good unit - hsoil:... and in-pot measurement is always best! .... as a back up, you can do a slurry test with the soils from the bag:
-- 1/2c soil + 1/2c RO/DI/low ppm water
-- mix and let sit for 30min
-- drain off some liquid and test with your pH meter (calibrated recently?)
... this will give a decent measure of that soils pH.....

Symptoms could be Ca defc. maybe P.. they can present similarly sometimes; a pH check is needed to see if it's a simple lack-of type defc. or a lockout...

 

[Kinezokyprios]

Typical magnesium deficiency due to overwatering, not so much a calcium deficiency. Your soil becomes very acidic. Actually I would expect this to happen on an outdoor plant that just faced a heavily rainy day and the next day is a hot sunny one, not on an indoor plant. Well led is the closest to sunlight, so it makes sense. Just give cal mag and it would be ok soon. Don't overdo it with water.