What might this be? Pics inside!

[crzygirl]

Have a 53 day flowerring monster, that just started showing these nasty looking leaves on the top main stalk only! I have not seen this crap happen on any other part of this plant.

My system is a recirculating DWC setup, currently with 8 gallons of water (4g. in nute res, and 4g. in the plant's bucket.)
Nutes are GH 3 part, but im doing Lucas formula at 50% so we havent given any GH Grow nute. Also added 1/2tsp of Florolicious Plus, and 4tsp of Kool Bloom
EC: Stable at 1.2
PPM: 820ish
PH: 5.9 (for now, seems to drift .1 to .2 a day)
Three two foot 20watt fluorescent tubes
One 250watt HPS
One 175watt MH
Room Temp: 72F during dark period, 75F during light period
RH: 36% to 48%

Roots look pretty damn clean. Like mentioned above, ph drifts down, but EC stays the same, and water usage isnt to much. Shouldnt the PPM/EC be going down and PH be going up cuz the top off water is plain tap water at 7.2ph...?

That would tell me that the plant is eating the nutes and water, not just, water. Anywho, the problem leaves kind of look like a Phosphorus def. What do you all think?

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EDIT: The system automatically tops off the resevoir with PH7.2 plain tap water, when the water inside the res gets low.

 

[Jim Dunlop]

Looks like heat stress. If that light in the picture is anything other than a fluoro I'd move it away fast! Usually when the leaves curl up like that its a sign of heat stress. Better ventillation, more distance between lights helps this out. Good luck!

 

[crzygirl]

JD - The light in the picture closest to that damaged top is indeed a 250watt HPS, but im not sure its heat stress though. I say this only because it has been in the same position as pictured (lights and plant) for more then a week now. I have tops that are all but inside my light hood/dome that arent even showing signs of heat probs. I will however hang my digi thermometer up there and monitor the temp up there tonight, could very well be heat stress. Have one 165cfm(maybe more) Can-Fan attached to the light thats closest to that top, and the other light is connected to a 400+ cfm squirrel cage blower. Also have a 20" regular standup oscillating fan that goes on full blast as soon as the lights go on and I open the doors (every night at 7pm).

I also wanted to add to my first post that this plant was grown from seed, and the water temps in the plants bucket and the res are 73.5 with no possible way to lower it. Now that the weather is getting cooler, I presume the water temps will reach the upper 60's by the time snow starts falling here.

 

[Skipload]

First, you said snow fall. I wish I could be there. Im not complaining, every day is the same in Southern California, but god its arid here.
There is heat stress, but it may not be due to the light, there is lock out showing and this will lower heat tolarance.
If your using Dry Kool Bloom, thats a serious dose.(off the top of my head). So I'm guessing your using liquid kool bloom.
Im guessing you haven't changed the res completely in a while. Start fresh.
The elements needed for your leaves, to correct the problem, isn't making it from your res to your leaves. You said your roots are still good, so reseting the res should be a good start.

 

[crzygirl]

Dang, we just did that last weekend too, started with a fresh batch of 50% lucas (6tsp Micro, 12tsp Bloom into 8gal. water then PH'd to 5.8), then 1/2tsp florolicious plus, and 4tsp liquid kool bloom

Maybe its the Kool Bloom causing this problem, as it just started showing on those leaves about four days ago. I should have stated the above, in my first post and I am sorry for not doing so.

 

[Skipload]

Is it only the leaves directly above the 250? Heat from a bulb rises, then rolls off the lamp, and out the front of it? Is that heat flowing up through the effected leaves? Theres three heat concerns to deal with
Radiant- the visible light given by the lamp
Convected- heated air from the bulb
Conducted- the hood

 

[crzygirl]

Yes its the leaves above the 250 watt hps, my lamps are in domes with a fan for each dome (2 domes total). Also, as I stated previously I turn on the oscillating fan every night at 7pm when the lights come on. Im leaning more towards this being a nute problem

 

[Skipload]

Why a Nute prob? Roots are looking good and all the nutes you use are quality products and not excessive. The only reason I mentioned nutes is because your instinct felt nutes where the problem, and I believe in instincts, so I mentioned the only thing I could do to rectify the problem if I was in the room as you, and was "going down whats wrong with my nutes road".
Now backing up with the info you gave me I feel confident it is the hot air coming out of the front of the lamp and burning them.

 

[crzygirl]

Im thinking nute problem because it happend 3 to 4 days after putting in 1/2tsp FP and 4tsp of LiquidKB, and the fact that no air comes out of the lamp because the fans suck air through the lamp and out of the grow area through the top of the box. The picture(taken on 10-4-08) shows the direction air flows through the hoods.

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Do you still think it could be the hot air though? There were a couple of leaves laying on the 250w dome, and those look the same as the others, all burnt up looking. Do nute problems always start at the bottom of the plant and move up? Never starting at the tops and moving down?