Diagnosis needed! Yellow new growth

[BooBooFace]

This is 3 week old transplants grown in rockwool.
RO water source brought up to 650 ppm when this was seen.
Temps run from 79 down to 66 degrees in sleep mode (6 hours per day)
Not all plants display this problem although all are not growing very quickly.
I'm using equal parts sVa and sVb nutes.
Humidity is running between 50 and 71 percent
And pH is right at 6.8

Any ideas? This seems severe as I see the yellowing in the edges of older leaves as well.[attachment=o279781][attachment=o279782]

[CanGroIt]

Are you using any micro nutes??? What's sVa and sVb???

CGI::::::

[silent leprechaun]

Hey
Im fairly new mysel but I think it could be either heat stress or a magnesium deficiency.

I'm not 100% but here is a link so you can self diagnose.

Plant Abuse Chart (http://www.drugs-forum.com/growfaq/97.htm)

You can check out my grow here: LED LOGGER (http://ledlogger.wordpress.com/)

I hope this helps.

Take care

[MEDEDCANNABIS]

This is 3 week old transplants grown in rockwool.
RO water source brought up to 650 ppm when this was seen.
Temps run from 79 down to 66 degrees in sleep mode (6 hours per day)
Not all plants display this problem although all are not growing very quickly.
I'm using equal parts sVa and sVb nutes.
Humidity is running between 50 and 71 percent
And pH is right at 6.8

Any ideas? This seems severe as I see the yellowing in the edges of older leaves as well.[attachment=o279781][attachment=o279782]

weeeelllll...ph should be 5.5 unless you trans into soil. humiditity is too high as well. ph has a huge factor in nute absorbtion be sure its close to what you need. im going to guess its your nute line...im not familiar with your nutes but im guessing thats the issue, as well as ph. overwatering could be a problem as well.