Help with an Auto Mazar Runt Please

[Peel Here Again]

I have four different strains growing right now and while the other three seem to be fine, I have an Auto Mazar runt that doesn't seem to like anything. I started all from seed and while the other three strain seeds germinated like champs, the Mazar struggled and I had to help her. She was slow popping out of the Jiffy pellet. Now, while the other three are huge and one week into flowering like dreams, the Mazar only recently showed sex and is now barely pre-flowering, and moving along slowly.

All the plants started showing signs of what looked to me like Magnesium deficiency a few weeks ago. I gave them 1 tsp per gallon of Magnesium Sulfate (Epson Salt) and they seemed to love it. The Mazar then started showing a lot of these rust colored blotches. I've researched this ad nauseum and still can't put my finger on it. I have some ideas, but want to see what others have to say. Temps and humidity are good. Soil Ph is good. Here are the vitals.

Strain: Dutch Passion Auto Mazar
Medium: Sunshine Advanced Mix #4
Containers: 3 gal. air pots
Area: 3x3 reflective tent
Light: 600w HPS+ @ 600 watts (air cooled)
Air exchange: Active intake and exhaust plus 6" fans inside
Distance from light: More than adequate
Temperature: High 60s to mid 70s F
Humidity: High 40s to low 50s % (with humidifier)
Water: Reverse Osmosis
pH IN: 6.5
pH RUNO: 6.7
Nutrients: None for first 3 weeks. Week 4 = AN Sensi Grow @ 50%. Week 5 = AN Sensi Grow @ 100 %. Week 6 = Only RO pH 6.5 water. Other AN supplements used include B-52, Voodoo Juice, Piranha, SensiZym, blackstrap molasses (all as directed).

While the three other girls look healthy and are flower making machines right now, this Mazar runt needs some help. My suspicions based on my research are nute burn, potassium deficiency, calcium deficiency, or manganese deficiency, but this is only my fourth grow and I'm no expert. Any help diagnosing and remedying this girl is greatly appreciated. :thumbs:

 

[namvet25]

http://www.growweedeasy.com/marijuana-symptoms-pictures It looks like a calcium and phosphurous diefiencey.Your ph is a little high try and drop it to 6.5.Then add some cacium and phos and see if that helps.

 

[Scott817]

I looks pretty mag/calcium defieicent. You need to drop you ph down to about 5.9 in veg with a soiless mix like sunshine. I had not see it come out higher as typically what goes in is what comes out when I use that medium, Remember soiless mixes are more like growing in hydro as you are feeding all the nutes via the water. You run a lower ph than soil and higher then reg hydro. I usally run 5.-7 - 5.9 in veg and 6.1-6.3 in bloom.

 

[Peel Here Again]

I've dropped my inbound pH a little lower and added Cal/Mag. Hopefully that does the trick. I'll let you know in a few days to a week how that worked. Thanks!

 

[Scott817]

If it gets worse you can make up a solution of water ph'd to 5.8 and cal/mag and do a foliar feeding. Just do it right before the lights go out.