Help verifying Magnesium Def

Good morning! I have what I think is Magnesium deficiency.

Indoor Grow, Sealed Room
Strain: OG Bubba (Indica)
Beginning of Week 6 Flower Cycle (12/12)
1000 Watt HPS
75 degrees F average temperature
50-55 relative humidity
Co2 running at 1150-1300 ppm
Hydroton Medium
Ebb-Flow bucket system
---Reservoir drained and cleaned every 2 weeks and filled with fresh nutes
---Plants watered every 4 hours during light cycle with Root immersion at 20-30 mins, none at
night
PPM's run ~1200
PH 5.8-7.0 (climbs 1 ph per 12 hour light cycle)
Using House Garden nutes in RO Water:
--Aqua Flakes A+B
--Roots Excelerator
--Algen Extract
--Drip Clean
--Bud XL
--Top Booster
--Multi-Zen every other week
--Little Cal-mag, not much

Started 2-3 days ago, leaf tips curling down a little but no color change. The plants were still rigid and not drooping, just the tips were curling down a little like they were getting over-watered maybe.

Then some of the fan leaves toward the top of the canopy started to get light yellow (looked like normal fan yellowing because we're in week 6 of flower).

The next step after the light yellow was the pictures you see here which appear to be magnesium deficiency I think.





Image not posting, here's the file shack link:
http://yfrog.com/50img087dj

Post pic!

But i can tell you right now, if you are using RO water, you should add small amount of calmag to your solution. What is the calmag you use and what ratio do you use it?
I personally use AN SensiCal Mg and it's a good product. I heard many great things about Botannicare CalMag+ as well.
Your ppm might be little high as well, depending on the strain and many other factor, 1200ppm can be little too much. With chemical nutes i tend to stay on the safe side to avoid burns.
And considering youre at 6th week of flowering, your plants might be asking for higher P-K ratio.

But a picture would definitely help.

Fixed the links for the pics.

I'm using Botannicare's Calmag+, 2ml/gallon.

The plants were eating up the 1200ppm (don't have any burning so far), but I'll be feathering back down to about 850ppm for week 6-8.

Edit: So far there's 3 leaves that look like this one (1 leaf on 3 different plants), and several other plants have started to have the light green bordering on yellow. The leaf in this picture looked light green bordering on yellow before the brownish color came in. Oh, and this is fan leafing at the top of the canopy. There's none of this at the mid or bottom of the plant.

bumpity bump

Goin home from work in an hour, hopin someone can confirm that the resolution is upping the cal-mag+ from 2ml/gal to like 4 or 5 ml/gallon

Looks like a potassium deficiency to me

http://en.wikipedia.org/wiki/Potassium_deficiency_(plants) Check it out

Potassium and Calicium def are similar but Since you already use 2ml/L of calmag+ i would say it's more a potassium def.
But let's think more about it. You are at 6th week of flowering, hydroponicaly grown, this might be the final stage of the plant and she start consuming the all the Nitrogen avail in the leaf and produce a final boost of growth.
The strain i work with M39, is fully developed in 45-50 days roughly(6 week).

I am just not sure..
Please post a full plant pic.

Xan2 said:

Potassium and Calicium def are similar but Since you already use 2ml/L of calmag+ i would say it's more a potassium def.
But let's think more about it. You are at 6th week of flowering, hydroponicaly grown, this might be the final stage of the plant and she start consuming the all the Nitrogen avail in the leaf and produce a final boost of growth.
The strain i work with M39, is fully developed in 45-50 days roughly(6 week).

I am just not sure..
Please post a full plant pic.

Click to expand...

yeah bro, that greyish purple shit on the fan leaves is most likely a potassium deficiency, magnesium usually makes them turn yellow and crinkle, nitrogen deficiency makes the lower leaves turn yellow and fall off, I hope the right ferts can save this guy's plants.

New development, my meter went out of whack right around the time the issue first popped up, it was reading high, so I was bringing my reservoir down to low 5's for several days thinking it was actually 5.7-5.8.

Recalibrated it last night, corrected the issue, as well as gave it shooting powder, and brought the PPM's down to 1000. Hopefully everything's corrected. They didn't look any worse before lights off this morning.

Edit: Shooting powder from house & garden being heavy P-K for the last 3 weeks. 30% of the grow exibited yellowing of 1-2 fan leaves that was a precursor to the bronzing. The rest of the grow doesn't show any signs of yellowing. Tomorrow morning I should know if I stopped further damage. Thanks for the input guys, because the onset of the bronzing was fast, the potassium suggestion led me to the meter being off.

...hey R2F, good tip for ya...I own 3 of the most respected pH meters outthere (Bluelabs, "Truncheon" pH meter, Bluelabs , "Combo" meter, and a milwalkee "Combo" meter)...I don't even use them....get yourself one of those liquid pH test kits made by, "General Hydroponics"....I started using it to double check my pH reading after every electronic meter reading....and now it's all that I use, it's bullet-proof and is the cheapest method...unless one is color blind. Good luck bro.

trichlone fiend said:

...hey R2F, good tip for ya...I own 3 of the most respected pH meters outthere (Bluelabs, "Truncheon" pH meter, Bluelabs , "Combo" meter, and a milwalkee "Combo" meter)...I don't even use them....get yourself one of those liquid pH test kits made by, "General Hydroponics"....I started using it to double check my pH reading after every electronic meter reading....and now it's all that I use, it's bullet-proof and is the cheapest method...unless one is color blind. Good luck bro.

Click to expand...

sometimes its hard to read the color cuz the nutes discolor it so much and throw your readings off though. I use my pH pen and the liquid pH tester though just to be double safe.

...you should be able to learn your color of an "inrange" reading early on to base your judgement on.

I am color blind and those drops were pain in the *** for me lol.. i rather use my pinpoint meter.

Was thinking about meter issues.

From a standpoint of ease of use, it's hard to beat the digital. But this last instance really opened my eyes. Maybe recalibrate once a week?

So the girls are going through the same amount of nutes, and the yellow leaves that were popping up at the top of the canopy are not bronzing, or if they bronzed, it was very minor. No affect below the top-most fan leaves.

This plant is extremely resilient.