Unknown early deficiency signs?

[bouillabaisse]

I can't seem to figure out what the problem with the leaves are, mild brown spots in the center of growth, no signs of any burning on the tips. I checked for mites but didn't find any. Only 1 plant is showing these symptoms, other 3 look perfectly healthy.
I'm trying LST for the 1st time so could this be stress symptoms?

2nd time growing, using a mixture of Fox farms ocean forest and perlite. Gave them straight tap water (my town has clean, mildly acidic tap water) for the first few weeks. Just recently started adding 1ml per gallon of gringo rasta cal mag and 2ml of big bloom.
1200w king LED light
78°F with lights on, about 70° off
40-45 rh on, 60-65 when off.

 

[Mañ'O'Green]

Fox Farm Ocean Forest grows come to the Infirmary often. It looks like the beginnings of a Cal-mag deficiency but since you are feeding cal-mag perhaps we need to look at PH. What is the PH in the root zone? If you do not have a good PH soil probe now is the time to get one. I recommend the Accurate 8 (or the clone of it) or Bluelab. Bluelab has several probes so be sure to get the correct one if you go that way.

 

[Groff]

Mildly acidic ?? That is very uncommon. Do you know the pH, or have public water test reports? Knowing your pH is essential, even in organic grows, contrary to popular belief - of course to a lesser extend than hydro, but still.

Of course you should diagnose as soon as possible to prevent issues, but I've had hundreds of plants show issues like this that ended up not being anything, just short term complaining. The key in knowing your medium well. This alone is subject to many-a-book.

LED is prone to cal-mag defs. Since you are supplementing with cal-mag, I'd say give it a few days and monitor

Damn, 1200w, is that real power draw? How many plants are your doing?
_

 

[bouillabaisse]

I bought a cheap ph test pen for my last grow and while the thing never accurately worked, I remember it reporting my tap water as being a lower ph than RO water, so my sources are questionable. I have read water reports though so I know I have very clean water.
It's a cheap chinese LED. I remember reading the 1200w is equivalent to 800w from a HID, but I'm growing 4 plants, would that still be considered overkill?

 

[bouillabaisse]

I have an old soul probe from my last grow, I'll dig it up tonight and get back to you. I just find it strange it's happening on one plant and not the other 3.

 

[McDee]

Fox Farm Ocean Forest grows come to the Infirmary often. It looks like the beginnings of a Cal-mag deficiency but since you are feeding cal-mag perhaps we need to look at PH. What is the PH in the root zone? If you do not have a good PH soil probe now is the time to get one. I recommend the Accurate 8 (or the clone of it) or Bluelab. Bluelab has several probes so be sure to get the correct one if you go that way.

Nailed it! Spot on listen to what he is telling you @bouillabaisse and if you are going to use Fox Farms I would use Happy Frog not as hot as OF.