Can't Pinpoint My Issue, Halp!

[begone_thought]

Hey dudes and dudettes.
Ive had almost not a single issue my entire grow but I'm about 3 weeks into flower and the more established leaves (I.E. not small and sugar leaves) have begun showing signs of what I THOUGHT was a Calcium or Magnesium deficiency.
I listened to the advice I've always seen given and I got a proper digital pH tester as well.
My setup is a 25L DWC with constant bubbles. I measure and top up every 2 days. And I use General Hydroponics Flora 3part series nutrients with half a tbsp CalMag every top up in a 10L bucket that I mix my nutrients in.

The results are as follows:
pH: 5.9
EC (in microSiemens): 2030 (I try to keep it as close to 1600 but it fluctuates a lot even in just 2 days. This has always been the case and I havent had any other problems like this before)
Temp in room: consistent 22 celcius, always.
Solution temp: about 19 celcius

I only started noticing this issue when I switched to 12/12 I'm not sure if flowering vs veg makes a difference.
I've included a few photos, I hope they help. And let me know if I havent included some important bits of information.

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[ricky4003]

Looks like nute burn to me,too much nutrients, even an EC of 1.6 is fairly high even at its growing stage. I very rarely go above an EC of 1.3 even in the late stages of flowering. I would flush the plants with plain water and then start your nutrients a lot lower than 1.6.

[begone_thought]

Looks like nute burn to me,too much nutrients, even an EC of 1.6 is fairly high even at its growing stage. I very rarely go above an EC of 1.3 even in the late stages of flowering. I would flush the plants with plain water and then start your nutrients a lot lower than 1.6.

Thanks for the reply. I've never done a flush before. How long do you recommend plain water before adding nutrients again? And should one still pH correct the water before flushing?

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[ricky4003]

No need to PH your water as they won't be taking any nutrients when you flush, though some people PH their water but I never do as the primary use of PH is to enable your plants to take up the right nutrients whilst growing. There is also no need to PH your water when you flush before harvest. As for length of time for flushing when you burn your plants well that depends on how high your EC is. With an EC of 1.6 I would flush for at least a week, but it can take up to a fortnight. Then I would add nutrients to give an EC reading of 1.0 and a PH reading of between 5.5-6.2. Monitor your nutrient levels every day and if the reading goes up then you are overfeeding and if it goes down you are underfeeding. If it constantly stays the same then your plants are happy.

[Trex]

Overfeed . Bring that down . Even 1600 is high . Its why it keeps climbing and ph drops like a rock

Lower that to 1.2 6.0ph and go from there buddy .

Keep us in the loop .

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[begone_thought]

No need to PH your water as they won't be taking any nutrients when you flush, though some people PH their water but I never do as the primary use of PH is to enable your plants to take up the right nutrients whilst growing. There is also no need to PH your water when you flush before harvest. As for length of time for flushing when you burn your plants well that depends on how high your EC is. With an EC of 1.6 I would flush for at least a week, but it can take up to a fortnight. Then I would add nutrients to give an EC reading of 1.0 and a PH reading of between 5.5-6.2. Monitor your nutrient levels every day and if the reading goes up then you are overfeeding and if it goes down you are underfeeding. If it constantly stays the same then your plants are happy.

That's some solid advice, especially regarding the EC and nutes. I want sure if it worked that way but that's a nifty thing to remember.

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[Jimster]

They look to be suffering from an overload of P or K, which can cause the leaf necrosis around the perimenter of the leaves. A lot of times you get yellowing of the larger leaves during flowering, but your's looks pretty good, so I think it might have too much Potassium. Too much P or K can interfere with the plant's ability to use other nutrients, causing a deficiency despite plenty of nutrients available in the soil/water. I grow in a soil type medium... I would probably flush them to try to remove excess nutrients, then re-introduce to a much lighter diet in the future.

[ricky4003]

Yep never go off manufacturers feeding charts as different strains of Cannabis have different nutrient uptake needs, some like a lot of nutes and others don't. If you follow the guidelines that I explained in my last post regarding nutrient levels you won't get any overfeeding/underfeeding problems.

[begone_thought]

Yep never go off manufacturers feeding charts as different strains of Cannabis have different nutrient uptake needs, some like a lot of nutes and others don't. If you follow the guidelines that I explained in my last post regarding nutrient levels you won't get any overfeeding/underfeeding problems.

The funny thing is, I'm having these problems with 35% strength of General Hydroponics guidelines. I originally started at 50%

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[ricky4003]

The funny thing is, I'm having these problems with 35% strength of General Hydroponics guidelines. I originally started at 50%

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It is still too much Nutrients, your leaves show this! Manufacturers always go way above the norm with their feeding schedules so that you use more Nutrients faster which in turn puts more money into their pockets. It's a fucking ruthless world out there and people will do anything to make a quick buck, so don't be fooled by their tactics.