potassium or nitrogen deficiency

[Smokey Mcpotster]

I've been reading and trying to figure out what my plants are telling me. I have been having trouble for a few weeks with the color being light green on some leaves. Some of what I have read mentions that not all plants will stay an even dark green. Is that true? When I look at the plants I see N def and possibly potassium. I'm getting mixed signals. Some leaf tips are curling down, some leaves are canoeing. The burn on the edges of the tips seems like nute burn but could be also be potassium def?.
I'm not sure if I should try to bring the ppm up or more cal mag?
Any help or advice would be great.

mandala satori and speed queen.
Vegged for 8 weeks.
600w hps
5 gal bucket dwc with 2 6" air stones in each bucket
Lucas formula currently at 700 ppm @ .5 conversion.
10ml calmag for 3 gal water in bucket.
temp. 75 lights on 65-66 lights off. Been on 12/12 for two days.
rh 40% or under.
Air exchange 4x per minute.

Edit: It seems to me that the branches are a bit weak near the top. Could this be from the new leaf and shoot growth weighing more than the new branch growth can support right now?

 

[Smokey Mcpotster]

Heres one more pic

 

[OldHippieChick]

I had that going on near the top new growth. I added more cal mg and it went away with two consecutive rounds. But don't take my word for anything - I'm greener than your leaves.

 

[Smokey Mcpotster]

Thanks OHC, I've read as much as I can about it for now. Too new/ inexperienced to go with my gut I guess, lol. I'm wondering if I need more nutes or cal-mag. My gut tells me they are lacking nitrogen, but I worry about to much N now that they are on 12/12. I had to put them into flower, their getting huge!!! I just want to make sure I make the right choice on how to adjust them.

 

[erkelsgoo420]

Up the cal mag and give them a little nitrogen and they should perk right back up... How's ur ph?

 

[ozzydiodude]

Looks to me like your PH is locking out Mag and/or zinc. Before you try changing nute make sure your PH is right.

 

[Smokey Mcpotster]

Welcome erkle. Thanks for the help.
Ph is at 6.1 up from 5.8 24 hrs ago. The one I checked drank about a half gallon but the ppm went from 820 (700ppm nutes + cal mag) to 650. This means they are using more nutes than water, right? wouldn't the ppm stay the same if they were taking in water an nutes at the same level. 2 questions, I am at 10 ml of cal mag per 3 gallons of water, should I up that to 15? seems a bit much at one time. Since I am using the lucas formula, how do I just add Nitrogen? Should I up my ppm to 750?

 

[Smokey Mcpotster]

Ozzy, I switched from a 3.5 gal bucket to a 5 gal. I have 50% more res. now. It went up .3 in 24 hrs. I was having worse swings with the 2 gal res, I have 3 gal in the 5. Also what do you see in the pic that tells you ph is off. Not questioning your experience, just want to know what you see, that I obv don't.

Thanks for the help!!!!

 

[ozzydiodude]

I thought in a DWC you ran a PH of 5.5 to 5.8. Any higher and nutes were getting locked out

 

[OldHippieChick]

:yeahthat: I am using GO and the instructions say 1 tsp per gallon for light feed and 2 tsp per gallon for heavy feed so that would be 15-30ml of calmg with mine...

 

[ozzydiodude]

When I see any type of deff the first thing I look at is PH. the chart is link shows when your PH is 5.8 mag starts to be locked out and 6.1 N starts to get locked out in Hydro

http://www.marijuanapassion.com/forum/attachment.php?attachmentid=1833&d=1141100090

 

[erkelsgoo420]

I let it climb from 5.4 up to sometimes 6.2 it locks certain nutes out at different points but it also increases uptake of different nutes at different points the trick is to not deprive them of any certain nute for too long and never over adjust the ph rapidly. Only made that mistake once

 

[PUFF MONKEY]

they look like they're praying for water too... what are your temps like ?

 

[Smokey Mcpotster]

Hey Puff, thanks for looking at this. Res temp is 65 degrees, that was after 10 hrs of light on cycle. I was able to keep it below 72 all thru 24/0 veg.

 

[The Hemp Goddess]

I would get my pH in line before I did anything else. You cannot even begin to start diagnosing deficiencies without a proper pH. I'm like erkelsgoo--I purposely let my pH drift some--I will start at about 5.3 and let it drift to about 6.0. I can tell you that Mandala's strains are very efficient in their nutrient uptake and need less nutes than other strains I have grown. I have grown both Speed Queen and Satori in DWC on just the Lucas Formula without any problems.

 

[Smokey Mcpotster]

Got it THG. I'll bump it down slowy, and start the new res when I get this down to 5.7 or a bit lower. I'll start it at 5.4ish.
Yeah I chose these 2 because they were easy to grow. :rofl:
I can tell you they take abuse well.

Thanks everyone. I'll get some pics once buds start to form.