HELP! What is causing these leaf spots?

[Rik]

Hey guys. Does anybody have an idea what is causing these spots on my leaves? These are OG Kush autos grown in FFOF/Nature’s Living Soil. The full details of this grow are below. Should I add some more Nature’s Living Soil as a top dressing to top up on nutes? Thanks for any suggestions!

Full details:

2 x OG Kush autos from Nirvana, indoors in a 4x4 tent
Age: About 6 weeks since sprouting
Soil: Fox Farm Ocean Forest with Nature’s Living Soil and perlite (“Living Soil” approach, not “Super Soil” approach)
Fed only water, a mix of spring and filtered drinking water that comes out at roughly 6.5 pH (I feed only water since I’m using living soil)
Light: Black Dog PhytoMAX-2 600 (615 watts from wall)
Temperature: Low 70s during lights off, mid 70s with lights on
Humidity: Upper 40s with lights off, low to mid 40s with lights on
Ventilation: 8” system with 710 CFM fan pulling through two separate large carbon filters (one tail end and one inline) through very long duct work, resulting in a nice breeze coming out in an adjacent room, and tent walls sucking in decently but not extremely hard
Small Vornado air circulator inside tent, blowing 24/7 on low, pointed slightly down to not be directly on leaves

 

[UndergroundFarmer]

It looks like a calcium deficiency.

 

[Canuck147]

Nutrient lockout - you're not adjusting the pH of the water. Even though you're not adding nutes - plant can't absorb the nutes in the soil if the pH is not between 5.5 - 6.5

 

[SoOrbudgal]

Agree with Canuck147. Not allowing plants to dry , mixed medium may of been to much juju during transplant on their roots. Now lockout.

 

[crucialbunny]

OG Kush is a notorious calcium/magnesium whore, I have 4 OG's going now so I've been adding lots of dark greens, legumes, and grains to my worm compost bin incase they show signs of deficiency.

 

[CaptainWiese91]

I see PH problems/root issues

 

[Rik]

Thanks everyone for the feedback! I’ll check again but my water usually comes out right at around 6.5, so I’m not sure what I can do about improving pH. What should I do to remedy the situation? Let it go longer to totally dry out? Add an organic cal-mag (is this okay with an organic Living Soil grow)? Something/anything else? Thanks for teaching me!

 

[Canuck147]

Buy a meter to check your pH.

 

[PLreef]

When I used living soil I picked up and used Roots Organic calcium additive. Seemed to work well.

 

[Rik]

Thanks! Just got some Roots Organic Cal-Mag at the hydro store. Should I use it every time I water? Every other time?

 

[PLreef]

Is it the powder type?

 

[Rik]

No it’s like this pink thick liquid

https://midwestgrowco.com/products/...I2BG8I8jekDknY_Y2vPeNE7TvaCCrkI0aArTVEALw_wcB