Issues with a flowering plant

[greents]

Friend got up one morning to find one of the plants on his table very droopy/lifeless. None of the other plants on the table are like this.

HYDROPONICS:

What STRAIN are you growing? Unknown
What was the establishing technique? Seed
What is the age of your plants?
What PHASE are the plants in? Flowering
What Technique are you using? Flood and drain
What substrate/medium are you using? Hydroton and rockwool
What is the Nutrient temperature? Unknown but not too cold or hot
What Nutrient's are you using? Gone from Aqua Flakes to FoxFarm along with blackstrap molasses (From what I understand, the FoxFarm nutrients being used are Tiger Bloom, Grow Big and Big Bloom.)
What is the TDS/EC/PPM you are using? Unknown
What is the pH of the "Tank"? 6.8
Are you sure your calibration is correct on your equipment? Yes
When was your last watering? Timer 3 times a day and once at night
When was your last feeding change? The switch from H&G to FoxFarm's on the 21st.
What size bulb are you using? 1k HPS
What is the distance to the canopy? 17-18inches
What is the canopy temperature? ~80
Have any pest chemicals been used? If so, What and When? Never
Are plant's infected with pest's? No

 

[Cruzin]

What is the TDS/EC/PPM you are using? Unknown

That is a problem. If its the only plant like this, it is likly to happen to the others or have the problem spread. My first thought was that it looked underfed, needed watered, but if you're using a flood tray i dont see that being likly since its the only plant like that.

 

[Mr. Greengenes]

I'm not a hydro guy, but that looks like a plant that recently lost a big part of it's root system. How is that plant different from the others? Is it smaller in size, in root system? Is it sitting in a place where it can't get as much oxygen at the roots as others? Are you sure the PH is still 6.8?

 

[greents]

The plant may have had some of its larger yellow fan leaves taken off prior to the droopiness (day before). Aside from that, not much different at all.

 

[Hazy Lady]

That PH is a full point too high, you need to be around 5.8 (+/- a .1 or .2), the plants are showing massive problems, the least of which is some droopy leaves, bring your PH down and watch them go!

 

[greents]

PH is still 6.8-6.9

 

[Hazy Lady]

But you are growing HYDRO? 6.8 is for soil grows.

 

[greents]

Should I suggest that he add water that is ~4.5-5.0 to his res?

 

[Hazy Lady]

Well the easiest way is to add PH down until 5.8, trust me the plants will explode, at 6.8 they are just, only just getting enough food to survive, he will lose a lot of his yield and potency if it is not rectified.