Leaf Curl problem - pictures and info included. Does too much CO2 cause curl?

Hello!

I am currently growing LA Conf and master-bubba. Im having a curl issue with the LA. Here is a few examples:



&



The master-bubba does not exhibit the curl. Example:



There is a overall curl on the LA (with one or two plants out of 20 as a exception). I thought perhaps it was heat/lighting causing it as that has caused curl for me in the past. However after moving the lights away and cycling them with good room temps (74-79 canopy temp) the curl has not straightened.

I have CO2 running at about .75 in terms of release pressure @ 12 hour cycles. I have a fan that redistributes the co2 across the 10ft long canopy. Is that too much? The room is not completely air-tight so there is some loss that occurs.

Here is my nutrient schedule:
GH 3-part at recommended flowering cycle doses
50ml diamond nector
25ml cal-mag (I use a RO)
Great White

These are about day 17 flowering cycle.

I have applied Bush Master in first week of flowering (two water/cal mag flush cycles) and then half-nutes with MOAB about day 12.

The watering schedule has been very adequate with no over-draught. I hand-water every other day, 3-gal buckets with PH around 6. The soil gets near-dry after 48 hours.

PS- The 'spots' you see are not thripes but milk residue. I gave it a try last week with a 25% milk/water mixture. Im looking for a really helpful addative to make the milk spot-stains not exist. Will baking soda help? Looking to spray weekly until about week 5-6 of bloom.

Any thoughts would be helpful.

Thanks

I have 9 clones right now at 6 weeks of age, they have curl. The last of my clones that curled I had to toss out.
Best I can figure is it is over watering. My plants go 4-5 days between watering I use a water moisture sensor and let it get near dry.
bring your PH up top dress with tblsp garden lime at next water.
add 1 tsp molasses every other water per gallon.
Could also be low humidity I run 40% at 78 degrees during light and 30% and 70 degrees dark.

Thanks. The curl is only happening in bloom. The veg stage they are super happy.

The rootbase is really thick so they definitely need watering every 2-3 days. They start to stress out if I do not, its pretty obvious.

Bring my PH up to what? And why the 'garden lime' and what precisely is that?

I have sweet, I can put that instead of the molasses right? And can sugar or the lack of cause curl?

johnd0857 said:

I have 9 clones right now at 6 weeks of age, they have curl. The last of my clones that curled I had to toss out.
Best I can figure is it is over watering. My plants go 4-5 days between watering I use a water moisture sensor and let it get near dry.
bring your PH up top dress with tblsp garden lime at next water.
add 1 tsp molasses every other water per gallon.
Could also be low humidity I run 40% at 78 degrees during light and 30% and 70 degrees dark.

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