Rust colored spots on new sprout

Not sure if this is the right place, but here we go! I just started some Gorilla Glue and am noticing a few small rust colored spots on the lowest leaves. This plant was planted Oct. 28th, so it’s still really young, but wondering if I need to be concerned.

  • Strain and seed type: Gorilla Glue Autoflower in 3 gallon fabric buckets with Happy Frog Soil
  • Medium (soil, hydroponic, etc.): Soil
  • PH of runoff or solution in reservoir: 6.51
  • Strength of nutrient mix, EC, or TDS: I use an automated drip feeder pulling from a 5 gallon bucket that is ph balanced at 6.2 with 6 tsp of Fox Farm Big Bloom (0-0.5-0.7). I started feeding it about 1L of fox farm grow big mix (6-4-4, 1 gallon water to 2 tsp grow big) twice a week this week. I noticed the spots before I started on the grow big, so I’m assuming it’s not related?
  • Indoor or outdoor: Indoor
  • Light system, size: 315 CMH light
  • Temperatures day, night: day 80-85, night 60-65
  • Humidity day, night: day 25-30, night: 15-25
  • Ventilation system (yes/no, size): yes, carbon filtered with forced air intake. Tent is under a negative pressure.
  • AC, humidifier, de-humidifier: no, but when I check them I spray the walls down with about 2 cups of water once a day to try to keep humidity up.
  • CO2 (yes/no): no

First of all welcome to the neighborhood. I think it’s calcium deficiency

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I started feeding it about 1L of fox farm grow big mix (6-4-4, 1 gallon water to 2 tsp grow big) twice a week this week

Should be 500ml’s twice weekly. Total it gets for the week of grow big is 1L.

Second look do you spray your plants like that with your lights on?

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Yeah, I usually spray them in the morning. I didn’t want to disturb their night cycle (lights are automated 18-6 cycle).

I still think that the brown spots are from low calcium but the lighter ones are probably light burn from spraying. The water droplets cause magnification of the light and burns the plant. It’s always best to spray at lights off, it’s not gonna hurt to turn on regular lights just as your lights go off to spray em. It’s during flower that its crucial not to interrupt the light cycle, plus you don’t want to spray buds anyways because they’ll hold the moisture and either mold or rot. Unless you’re fighting against bugs or disease you don’t have a choice but to spray em. The only time I can think of that you would spray with lights on is when using milk

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Oh that’s fascinating, I never considered the water could cause light burn, but that makes sense. I’ll only do it during the night cycle now. Do you have any calcium supplements you can recommend? I see Fox Farm makes a Cal-Mag supplement, I figure it might be good?

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I really like ff products and I always recommend that you stick with the same brand that you are already using. So short answer is yes

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I’ve had good luck with FF too, although this is only my second grow, so I clearly have a lot to learn. Thank you so much, I’ll give this a shot!

I use the same one and have not had any problems with it

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