Copied from roll it up; I haven't gotten much help!
Light: QB 240W LM301H + Epistar 660NM @ 26" from canopy - Dimmer set to 70%
Tent : 2.3' x 2.3' x 5.3'
Ventilation: 2x 6" fans - below and above canopy
Exhaust: Hyperfan V2 6" + Carbon Air Filter
Intake: Passive
Temp/Humidity: Day 25-27c @ 50-55% RH / Night 18-20c @ 50-55% RH
Medium: Promix BX + 60-80% perlite + Dolomite lime (1tbsp / gal)
Water: Tap - 150PPM @ 19c - left out for 24hours
Containers: 3x 2gal - 1x 3gal
Stage of growth: 6 weeks, veg, 6" tall
Strain: Wedding Cake - Feminized
Nutrients: Botanicare Pure Blend Pro Grow (9ml/gal) + Liquid Karma(3ml/gal) + Cal-mag plus (3ml/gal)
Feeding: 950PPM every water until 10-15% runoff @ 6.3-6.4 pH - every 3-5 days
Runoff PPM & PH: I haven't measured runoff PPM or pH in a few weeks. Last check the runoff pH was @ 6.4
Pests: Fungal gnats treated with yellow sticky traps
Symptoms: Yellowing of leaves starting halfway up the plant and browning rust spots. Lower leaves are unaffected.
Suspected issues: pH fluctuations, cal-mag deficiency, light intensity
These girls are just over 6 weeks old. They were stunted early on as a result of improper watering/feeding, too much perlite (causing the roots to grow only near the bottom of the pot), and reusing soil that was void of any nutrients (I baked it in the sun before reusing).
In the last 3 weeks they have been growing at a healthy rate. However, last feed I started to give them cal mag after noticing some rusty colored spots.
3 plants are in 2gal pots, 1 was recently transplanted to a 3 gal. I plan on transplanting the 3 plants to 3gal pots before next watering.
Any help is appreciated,
Thank you
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Hope you had a good vacation!
After watering (no nutrients) at a pH of 6.9 tonight, the runoff pH was 6.4, and the runoff PPM was around 620.
Well I think I've found one of the issues. I transplanted 2 more plants and watered them at pH 6.5 then checked the runoff pH that was sitting around 5.8. Time for some baking soda! I'm going to aim for 7.1-7.2 when I water them next time.
Awesome, thanks for your input. I'll raise the temps to 82 plus I've already got an IR thermometer so I'll keep an eye on the leaf temps. Raising the humidity may be the only real challenge.
Thanks again
Also, I lowered the speed on my inline exhaust fan to increase the temp and humidity. It's a 4 inch and its at a quarter power but still plenty to exchange the air at least every 3 minutes but no more than 1 minute per square foot
I had this same problem. Here's what I did:
I raised the temp from an average of 77F during the day to 82F. I run LED's and my leaf temp was running about 2 degrees lower than ambient temp. That combined with low humidity, at 55 to 60%, was I think the culprit.
I raised RH to 70%. Leaf temp at 82 and RH at 70% and they loved the change! They perked up in 24 hours after the environment change. (You can buy a IR thermometer off of Amazon to read the leaf temps)
I really let them dry out. I was watering every 3 to 4 days and I think it was slightly too much. Now its every 5 days minimum.
I also had the calmag issue. I'm running R/O water under an LED. Sounds like both a cal and mag issue in your case. 3ml per gallon worked for me.
I hope this helps!