Yellowing, Browning - all plants effected

Please help. These 8 plants are going the way of the previous 8 in that room. We don't want these to die, too. Here are some specifics about the room and pics included. The roots dont look great and the plants dont seem to be growing quickly if much at all. We have two other systems exactly the same nutrients & system and they are doing fine , but they are in different areas. We feel this is an environment problem. The conditions have been 100 degrees and 20-30% humidity.
We have now fixed this today, but if this is the problem, how soon should we see improvements? and would those conditions cause nutrient blockage?

What could it be?


[attachment=o264531]

[attachment=o264532]

[attachment=o264534]

[attachment=o264533]

E-indoor or outdoor - Indoor

E-soil, soilless, coco, aero, or hydroponic - Aero - 8 site bucket with sprayers

E-specific medium - hydroton

E-Water source - 10 gallon reservoir

E-Source water pH - 6.8

E-Age of plant - 3 weeks into bloom

E-Type of fertilizer - Budswell liquid bat guano & GH recirculating Flora Series

E-Lighting source and distance from plant - 9"

E-Air temperature (both day and night if you are running a dark period) - day 80-90 degrees F . night - 80 degrees

HD-Reservoir temperature

E-Air % Relative humidity - 20 % -38% - we have 3 humidifiers going constantly though

E-Lighting schedule - 12/12

E-Type of ventilation your room has - forced air with ducting to cool lights

I dont grow yur way my pilgrem friend and since yu be patient for a response and not gettin one I be tryin hard to help ya out! My only thing I have fur ya is yu mentioned temps bein 100 not good I be thinkin fur any grow conditions fur to long. I be hopin that some pilgrem who be growin yur way will help soon but get yur temps under control until they get here. Circle yur wagon and wait fur help. Hope yu get help and fix what ails ya wish I could be more help.

BWD

If I were you I would break out the jewelers eye. Spider mites or fungus gnats it's hard to tell in the pictures. One female gnat will lay up to 300 eggs that larvae will feed on your roots, the mites will suck the life from the plant from the underside of the leaf. Either way that would be the 1st thing I look for. Act fast these could be deadly if that's the problem.

Good Luck!

Honestly that looks like some type of nitrogen problem. Yellowing leaves is usually caused by either nitrogen overdose or nitrogen lockout. You say you have your PH at 6.8? I'm guessing by that your having nutrient lockout from your PH being too high. I would try balancing that down to 6.0. 6.8 is a bit high for that type of grow. What type of nutrients are you using? if your over nuteing the plants that could be an issue too. Do you have a PPM meter? if so what is your PPM at? You want your PPM to be around 1200 in the first weeks of flower. I would say its a safe guess that its caused by your PH being too high though. Try bringing your PH down and let me know if that helps.

Yes, PH I have made sure to be at 6.0 .. It was 5.8 for a day and then I got it back to 6.0 to 6.2...
PPM has been 1000 to 1600.
The humidity was the biggest problem on this run. It got as low as 20% for about a week till I got it under control.
Could there be a virus or infection in the room? Or a fungus perhaps?