COCO COIR What is happening to my babies? Nitrogen tox? Light stress? Overwatering? All 3?

[dudeQuixote]

My first grow.

Yesterday morning:


This morning:


AMS Northern Lights XTRM Auto-fem (And we know that the auto part was untrue at the very least)
They are in 2 gallon fabric pots, under a 315CMH and a dinky T5HO.
I haven't seen the temp top 80 yet, but it's getting close with the new lamp.
RH has been between 45 and 60.

Today is day 54 from seed. They were supposed to have been autos, but whatever.
Looking back on the last couple of weeks I've been fertigating on tuesdays and saturdays, and they maybe weren't as light and dry as they should have been. So maybe a little overwatering.
I'm using Canna Coco A&B at about half strength (20ml/gal), and cal-mag at about 5ml/gal.
My water is tap water that sits in a bucket with an airstone for a couple of days before I mix it up.
pH has been ~6 for the entire grow.

My cheap-assed CMH lamp burned out saturday and the replacement arrived wednesday, and the symptoms started showing friday. Before this morning, the lamp was ~18" above the tops. Now it's ~25". The symptoms are worst directly under the big light. I'm thinking maybe the cheap ushio lamp I bought last week is a lot brighter than the cheap POS topolite sent me.

Only 1 plant currently not showing these symptoms, out of the 5.

I'm thinking, flush them today with plain PH'd water, leave the lights up high and hope for the best. Any ideas?

[Brandon]

Your leaves are kind of all over the place on signs of issues, some have claw "downward curl at tip" which can be over watering, The buned ones have tacoing ( upward closing)which is a sign of heat and/or light light stress, plus the yellowing and burned sections really suggest light stress was your other CMH very old? the leaves look really shinny, did you by chance spray them with the light on either foliar feeding or insecticide?

[dudeQuixote]

I got in a bit of a hurry and might have spilled some nute-water on some of the leaves while feeding the other day. No insecticide. The other lamp wasn't old, but it was topolite garbage. The ballast they sold me lasted less than a month, so I assume the lamp was just garbage. The good news is after I raised the light, the symptoms have not progressed. I definitely made a mistake when I plugged the new lamp in without changing the height, and walked away for the night. The difference in heat output is very noticeable.

I didn't do anything to them yesterday other than spread them out a bit and raise the lights. Since nothing has gotten worse, I'm planning on flushing them today with plain ph'd water.
Should I give them a day or two before I prune the affected leaves?
The dark, glossy, downturned leaves is what led me to the 'nitrogen toxicity', but I'm not sure how that would happen with the way I feed them, especially lacking the burned tips you would expect with nute burn. Crazy thing is how all these symptoms popped up over 2 or 3 days. (edit: probably not that crazy when you factor in the lamp replacement)

[Brandon]

If they are in veg then normal pruning should be fine, but in flower once the stress gets over the tipping point that's when you will see herming and banana's, so if in veg continue on, if in bloom let them chill for a bit. If your old light sucked then light stress is highly probable as they just were not used to the intensity. Nutrient toxicity could be caused by low light intensity as the plant can't process the nutrients and they build up over time. Raising the light was a good idea, if you can get a PAR meter set the light so the intensity at the center of the light at canopy level is around 800µmol to 900µmol at maximum but 700µmol to 800µmol is safer. later you can play around and boost that up but you have to have good cooling, air flow and pay close attention to the tops as they can burn or bleach out. You will need to move the light up or train the tops to be lower as they stretch in bloom to avoid this taking daily readings at the highest points is needed. If you run out of space to raise the light just bend the top over a touch lower than what you want your max par exposure to be.

Without tip burn I would not guess over feeding, especially not nitrogen, I would however test your run off ph and ppm because you changed the lights, if your ppm starts to drop in your run off with normal feeding you may want to increase your nutrients by a small amount ( 5% at a time watching for tip burn) to get it leveled back out or do an early foliar feed as the light comes on but you have to use a wetting agent and a fine misting will do, that's likely what happened to your leaves that show the most burn because I noticed they were not all near the top where the light is most intense, the water you spilled formed droplets and that burns the leaves under full intensity, don't soak them you want them to suck it up like morning dew before the light gets to full intensity.

[dudeQuixote]

They are definitely still vegging, I thought I had autos, so they've been on a 20/4 schedule for ~50 days. I plan on flipping them after they recover from this.