FogFarms
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Intro & Background
Greetings growers! I am first-time grower who went straight to full-cycle fogponics growing. I need help identifying recurring brown/rust-colored spots on leaves. These spots start small and grow, eventually overcoming and killing the leaves. They seem to start all over the leaf, usually towards the center but not directly on the main vein, sometimes at the tips but certainly not always.
I strongly suspect a nutrient deficiency of some kind because: A) the problem seems to be slightly alleviated after feeding in terms of development of new spots; B) it was present even at very low nutrient levels; C) it disproportionately effects old growth (although may effect all but the newest growth to a much lesser degree).
However, I've raised my general nutrient profile to the point where I'm beginning to see mild nitrogen burn (or some kind of tip yellowing anyway), so raising my entire nutrient profile to solve this is no longer an option. I have to identify the specific deficiency and account for it.
I have researched this and found some people with similar problems (for example, this guy) but haven't really found a straight answer in their threads. pH imbalance was commonly suggested, but I watch my pH closely and it's never above 6.5 or below 5.5. Almost always 5.8 - 6.1. Maybe fogponics has a different ideal pH than hydroponics? I don't think so though. Magnesium and Potassium, maybe even Phosphorous, deficiencies are also possible culprits due to somewhat low Mag concentration in CaliMagic and low amount of FloraBloom fed in my profile, but I would like informed feedback before making further changes.
Images & Associated Conditions
Nutrient profile: 35% FloraGro, 35% FloraMicro, 17% FloraBloom, 9% RapidStart, 4% Floralicious Plus.
Full Conditions
The issue has presented under the following conditions, spanning 3 weeks. It was worst in the first of these weeks, when overall nutrient concentration was lowest and lights were strongest:
Been wringing my brain out over this and researching extensively to little effect. It's actually not the biggest issue now since the plants are growing rapidly and constantly growing new leaves at this stage anyway, and all their existing fan leaves would die or be cut off within a short time anyway. But I'm approaching flowering, and clearly need to get all my issues under control before then. Any input is greatly appreciated! (Even if it doesn't directly relate to the brown spots - but mostly that's what I need.)
Greetings growers! I am first-time grower who went straight to full-cycle fogponics growing. I need help identifying recurring brown/rust-colored spots on leaves. These spots start small and grow, eventually overcoming and killing the leaves. They seem to start all over the leaf, usually towards the center but not directly on the main vein, sometimes at the tips but certainly not always.
I strongly suspect a nutrient deficiency of some kind because: A) the problem seems to be slightly alleviated after feeding in terms of development of new spots; B) it was present even at very low nutrient levels; C) it disproportionately effects old growth (although may effect all but the newest growth to a much lesser degree).
However, I've raised my general nutrient profile to the point where I'm beginning to see mild nitrogen burn (or some kind of tip yellowing anyway), so raising my entire nutrient profile to solve this is no longer an option. I have to identify the specific deficiency and account for it.
I have researched this and found some people with similar problems (for example, this guy) but haven't really found a straight answer in their threads. pH imbalance was commonly suggested, but I watch my pH closely and it's never above 6.5 or below 5.5. Almost always 5.8 - 6.1. Maybe fogponics has a different ideal pH than hydroponics? I don't think so though. Magnesium and Potassium, maybe even Phosphorous, deficiencies are also possible culprits due to somewhat low Mag concentration in CaliMagic and low amount of FloraBloom fed in my profile, but I would like informed feedback before making further changes.
Images & Associated Conditions
- Feb 9th: https://invalid.com/a/8qINIyJ (250 ppm Nutrient Mix / ~90ppm CaliMagic, pH 5.8 - 6.5, PPFD ~800)
- Feb 15th: https://invalid.com/a/158fhZh (300 ppm Nutrient Mix / 300ppm CaliMagic, pH 5.5 - 6.5, PPFD 2000+)
- Feb 22nd: https://invalid.com/a/c1lon4Q (800ppm Nutrient Mix / 300ppm CaliMagic, pH 5.5 - 6.0, PPFD ~1000. Note the yellowing tips as well. In the second full-plant image, those wilting fan leaves I accidentally damaged during training, not due to nutrient issues.)
Nutrient profile: 35% FloraGro, 35% FloraMicro, 17% FloraBloom, 9% RapidStart, 4% Floralicious Plus.
Full Conditions
The issue has presented under the following conditions, spanning 3 weeks. It was worst in the first of these weeks, when overall nutrient concentration was lowest and lights were strongest:
- Daytime Conditions: 0.8 VPD, 30 C / 86 F, 79% RH
- Nighttime Conditions: 0.8 VPD, 26 C / 78.8 F, 74% RH (Note that RH dips considerably below this twice per night when I bring fresh air in. As I supplement CO2 during the day, it's not an option then.)
- CO2 Supplementation: 1500 ppm
- Medium: Air / Fog (Not Mist) / Neoprene Collar
- pH: 5.5 - 6.5
- PPM: Currently ~1100 (300ppm CaliMagic), which is beginning to show signs of mild nutrient burn (Nitrogen I believe), so I'll be diluting down to 1000ppm (300ppm CaliMagic).
- EC Scale: 2x ppm reading
- PPFD: 800 - 2000+ (Excessive I know, but clearly not the cause since I've raised the lights considerably since)
- Lights: HLG 135w QB V2, one per plant
- Leaf Surface Temperature: The issue has presented on leaves ranging from 23 C to 31 C.
- Root Zone Temperature: 25 - 30 C; which I know should present problems like root rot in conventional systems, but the roots are all white, hairy, happy, and abundant. Unless temperature may effect uptake of specific nutrients? But my understanding was that high root temperatures are only undesirable due to root rot susceptibility, which the highly-aerobic fogponic environment seems to prevent (so far).
- Strain: Special Kush #1 by Royal Queen Seeds
- Additional Info: First week or two I had the classic new-grower mistake of overfeeding, as well as grow room temps up at 40.5 C / 105 F because my controller code was faulty; week 3 I went too far in the other direction and underfed. Basically these plants have been through hell but I don't think their early-life problems are the cause of the brown spots. There is also some algae growth in the system which I'm currently in the process of blocking all light from. It's also worth noting that they appear to be quite happy aside from the brown spots, growing very rapidly. They're also undergoing training and shaping into a manifold as per Nebula Manifold technique.
Been wringing my brain out over this and researching extensively to little effect. It's actually not the biggest issue now since the plants are growing rapidly and constantly growing new leaves at this stage anyway, and all their existing fan leaves would die or be cut off within a short time anyway. But I'm approaching flowering, and clearly need to get all my issues under control before then. Any input is greatly appreciated! (Even if it doesn't directly relate to the brown spots - but mostly that's what I need.)
