Light coercion

Set the temperature for 80-85 degrees.

If you improved, good.. keep your light 14-18 inches above your plants.

That isn't too much light. 155 W from the wall in an 80x80 tent is roughly 545 PPFD on average, a little under what veg wants (600 to 900). At 60 cm it's spread evenly too, so I wouldn't change the light. Light stress usually shows as the top leaves folding up like a taco, bleaching, or crispy edges on the leaves closest to the light. Twisted new growth is more often something else. If it's only the newest leaves, look at them with a loupe for tiny mites, and think about whether anything new went into the feed or onto the leaves lately. ndsgrow's point about the pots never drying out is worth checking too. If it's an auto, BlaKX could be right that it's just starting to flower.

18h / 35-40 DLI 600 *.64 = 384umol/s PAR -- good initial target for 18 hours. 12h / 35-40 DLI 900 * .64 = 576 umol/s PAR -- good initial target for 12 hours. Divide those numbers by your total umol/s PAR output of lights and that's the power percentage you want for that light. Unfortunately, a lot of lightmanufacturer's lie on their spec sheet. Good luck. The math is only a good starting point. temp, rh and co2 all impact 'max' DLI you can give without damaging the plant. Observe and adjsut based on growth.. not the math. this light is likely too weak for 12 hour operation. Hope it's an autoflower

Hello Growmie, To me, it looks like an Automatic that is transitioning into pre-flowering. That's why there are discolorations on the newly formed shoots. If it were too much light influence, the leaves would start to curl, the edges would point upwards, and they would take on the typical canoe or taco shape. With the right light and heat, your leaves also fade, known as bleaching! RECOMMENDATION!: The distance from the LED should be at least 20cm+; during late flowering, you can go closer! The main thing is that the ppfd value is not too high! The Photone app can help! IT'S MUCH EASIER to hang the LED lamp fixed in one place and adjust the power with a controller or RJ12 connection with 1% accuracy. Many will surely come with the argument that hanging the lamp higher or lower is just as easy, but I disagree because a manual adjustment via a driver that only allows settings of 40, 50, 60, 80, 100% power will always have the problem of hitting the exact height. With the LUMii XLEDv6 680W at a typical distance (about 45–50 cm over 1.20 × 1.20 m), to achieve a PPFD value of 150 to 250 µmol/m²/s, you need about 15% to 25% power (about 100 to 170 watts). Since the minimum dimming for manual adjustment on the driver is at 40% (260 watts), you need to control this low range directly via the 0–10V/RJ12 signal from your controller or increase the distance to the seedlings. The danger is that especially at the beginning, too much ppfd value is driven, which leads to small dwarfs burning, especially with Autoflower. PS: I intentionally mistreated plants with too much light or spectrum to see the effects! Especially with UV 365-370nm lighting, there is a great danger of genetic defects or damage to the genetic material. I started growing again almost 2 years ago and had to switch from HPS to LED! This is possible thanks to spectra like deep red 660nm or infrared 730-745nm along with UV 365-370nm. I have documented everything sufficiently on my profile regarding which spectra, how long, and how many watts. LIGHT = WEIGHT (but only if you have DLI in the optimal range, whether with or without CO2). Sorry, my ADHD kicked in a bit! Hope I could help, best regards, blakx

It should say this I think.. Title: Light Stress Post: My tent is 80cm × 80cm × 120cm, and the light distance is 60cm. I just adjusted the PPFD yesterday. The actual power draw of the light is 155W. Is this causing light stress?

Lime-Green / Pale Growth at the Top (New Tops): The newest growth at the tops and inner nodes is noticeably lighter yellow-green compared to the darker fan leaves below. Downward Leaf Drooping / Curving (Heavy Appearance): The leaves have a swollen, slightly downward-drooping appearance (turgid curving rather than limp Wilting). Dense Canopy Density: The canopy is extremely bushy with minimal airflow penetrating the lower foliage. Likely Causes & Potential Issues 1. Light Stress / Rapid Growth vs. Iron/Micro-Nutrient Mobility Symptom: Bright lime-green new leaves at the very top shoot tips. Explanation: Under strong lighting (high PPFD), rapid vegetative growth can outpace the plant's ability to transport immobile micronutrients (like Iron or Zinc) or Sulfur quickly enough into new growth cells. Alternatively, if your pH is drifting slightly outside the sweet spot (e.g., above 6.5 in soil/coco or below 5.8), micronutrient lockouts are common even if nutrients are present in the substrate. 2. Overwatering or Substrate Aeration / Root Hypoxia Symptom: Leaves look full and heavy but curve downward ("clawing" or heavy drooping). Explanation: When roots stay saturated for too long, oxygen levels in the root zone drop (hypoxia). This prevents effective nutrient transport and leads to heavy, downward-curved leaves. Overwatering also impairs the intake of Iron and Calcium/Magnesium, further contributing to pale upper leaves. 3. Light Intensity / Distance (DLI Too High) Symptom: Tops bleached light green, tight node spacing. Explanation: If your LED light is running a bit too high in intensity or is too close, it degrades chlorophyll in the newest tissue before it can fully form, causing light bleaching/chlorosis at the top canopy. Recommended Action Steps Check Substrate Moisture: Ensure the pot has a proper wet/dry cycle. Let the top few inches dry out before the next watering to allow root oxygenation. Verify Root Zone pH & EC: Check input pH and measure runoff pH/EC to rule out pH drift or early salt buildup. Adjust Light Distance/PPFD: Check your current PPFD/DLI at the highest canopy tip. If PPFD is pushing above recommended veg levels, dim or raise the fixture slightly to give the new growth time to catch up. Defoliate / Airflow: Lightly clear out interior fan leaves that block airflow or trap humidity around the lower stems to prevent stagnant microclimates.

I got you. A distance of 60 cm at 150 watts is totally fine. I would even lower the light by another 10 cm. To me, it looks more like the pots never get a chance to dry out properly and the soil stays constantly wet (watering issue). I’d rather water a little more at once and then let the soil dry out properly than water every two days with 1 liter or so. That’s what your plants look like to me. If you have any questions, feel free to send me a PM!

Hi, I didn't understand the measurements here: ''the light distance is 6The ppfd I just improved yesterday0cm'' The light distance has many factors to keep in mind not just ppfd, also the bud zone temparature which should not burn the plant leaves. Of course too far away light can cause problems too, but I don't see a light deficiency issue here solely from this photo. Is this an auto or photoperiod? Just go easy around 400 to 700 ppfd and if you're using led lights try to keep the distance roughly around 40-50 cm I'd say. But these numbers are just estimations. I don't see a critical leaf twisting here. I'd recommend some defoliation of big leaves, not too many just a few from the middle part to allow air to flow smoothly and also let the plant spend more energy on the future bud sites instead of the leaves. It can boost the growth rate at this stage. Just try not to adjust many things dramatically at once. Often times less is more. Once you see the bud sites developing then gradually increase the lighting. One critical thing is to water properly, not too much not too less. Happy growing!