Week 3 Flowering: Blue Dream Older Leaves Are Dying Already

I'm in Week 3 of my Blue Dream batch. The older and larger fan leaves are turning into this dark greenish/brownish color, crispy, and dying. Newer leaves and the buds are fine.

Any ideas?

Setup: Custom recirculating drip system (modified ebb/flow system)
Nutes: Botanicare CNS17 Bloom, Liquid Kharma, Pure Blend. Around 500ppm all together.
Ph: 5.5 ~ 6.3
Water temp: 67 degrees (water chiller maintained)
Lights: 1000 watts
C02: 1450 ppm
Temp: 78 degrees at lights on / 64 degrees at lights off.
Humidity: 55%


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looks like nutrient burn to me

I thought about that but the new and fresh leaves doesn't have any burnt tips. Just the older bigger ones are affected by this...

yea cant be burn then, hows your air, temp humidity and airflow in the room?? do u have exhaust?

This can b a nute burn. When ur having a nute burn u can have a couple nodes grow before the burning spreads to them so the new leaves being unburnt doesnt mean its not nutes. Ur problem is either nutes or water ph most likely. Test the water ph first because u can do that in minutes. If its not that then flush it. U wont know if the flush has any effect for a while.

I went ahead with a flush using some leftover Florakleen. I just started and I'll let it go till in the morning (~10 hours). All my air, temp, etc information is on the initial post. Airflow is pretty good. I have a standing tall fan and a hanging one both circulating. I only vent out when the lights go out. Otherwise, it's completely air tight during when the lights are on. Would that cause any issues?

I'm growing BD as well and like you I am also in week 3 of flowering. My lower fan leaves developed a yellow tinge just like yours, and a few others looked like this with brown spots. I diagnosed it as a cal/mag deficiency, corrected it a few days ago, and now they're doing great! Make sure your pH is spot on and grab a cal/mag booster--could help.

I added some pics below of what my leaves looked like--mind you not all of them are Blue Dream.

FattyCaps

I'm running RO water and my initial ppm is around 15ppm. How much cal/mag do you use? ppm-wise?

Thanks for all the replies

-Dre

about 5-10 ml. I use 5ml along with a good a+b nutrient line. How crowded are your plants, especially the lower growth were you are experiencing the problems? Pics?

I'd say the OP definitely has an interesting issue.

500ppm is usually about 1.0EC... which is low enough that I don't think it should be Nutrient burn. Not severe nutrient burn, especially on a drip system. I suppose it could be related to a pH imbalance that locked up some salt in the rock wool which flushed through a while ago and you're now playing "catch up" on a problem that has come and gone.

If you had a pH issue in the past, lets say, 18 days or so then that's probably it. If you were running more like 800 to 1000ppm at the end of veg, that could be it too... Just now rearing its head.

I think since you already have a good deal of Botanicare nutrients I think a little ClearX might be a wise purchase for you, if not for anything other than peace of mind. So long as the new growth stays healthy then I think you'll be okay. Definitely keep an eye on your Phosphorus levels as a deficiency can sometimes begin looking similar to nutrient burn... Phosphorus is an important component of ATP, the molecule responsible for transportation of energy in the plant. As hormone levels increase in the plant the cells begin working a little harder generating energy to build flowers.

Often times nutrient burns are actually the result of an over abundance of one element, like Potassium, competing for uptake with another element like Magnesium. The Potassium salts build up and the Magnesium the chlorophyll requires is unavailable. So in order to build new leaves and grow the plant has to cannibalize itself, resulting in the interveinal chlorisis that accompanies most nutrient burn.

In that case you wouldn't solve the problem by adding more Magnesium. You'd need to remove the excess Potassium, which is why we call it a build up rather than a deficiency (despite the actual problem).

In this case I'm not entire sure what has built up, if anything, and if it is still there at all. Just be aware of the increasing needs for phosphorus and magnesium with decreased needs for nitrogen and calcium as you progress in flowering, keep that pH in line, maybe add some ClearX to flush the system a little bit, and I think things will wind up okay.