COCO COIR Leave tips turnings yellow

[Cocam360]

Hello.

We are into our second grow.
Leaf tips start turning brown and eventually works it way to the sides of the leaf.
It seems to start happening into the second week of flower. This is the second time the same thing has happened.
This time around we increased the nutrients, increased water, added molasses. This time it’s not as bad but It is still happening. We are growing Cheese and trainwrech. It seems to be worse on the cheese.
Your advise is needed, anything you can suggest will be appreciated.

We use fox farm 3 Nutes
just below their feed schedule
feed twice a week
5x5 grow tent
RO water
cal-mag 100-150ppm
PH is 5.5-5.8
humidity 60%
CO2
2 600w LED lights on a light mover

 

[Canuck147]

Your plants are looking pretty good actually. Except for that yellowing. My guess is you are using regular or even fancy molasses. Both of those has sulfur in it. The sulfur is causing the yellowing to happen. Organic or unsulphered molasses is what you want to use.

 

[Cocam360]

Hmmm, we are using unsulpherd molasses, maybe we should increase the amount.
right now we are using 1Tbl per gallon

 

[Sheesh]

Looks like possible nute burn to me. You say you feed just below the FF schedule? That is a hot feed mix, IMO. What's your EC or PPM? I'd recommend more frequent feeding in coco too. Try a flush with something like gh florakleen then reduce feed to 1/2 ff schedule. That with more frequent feedings should help.

 

[Cocam360]

Hey Sheesh
thanks for the info. I was having an issue logging in.
we did the flush and cut the nutes in half.
RO water is at about 35
add calmag to 150
after adding the half strength nutes total PPM is at about 885.
Didn’t see much change. The tips are now starting to turn brown on our other plants, they are just past 3 weeks into flower. This is so frustrating. Do you it is a potassium dificiency?