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Severe discoloration/light burn?

B

Bewi

Member
Im in week 4 now since germination. I have had problems pretty much since the start of the lifespan.

I am using GHE trio dwc setup.

Running at near 700ppm now, its about half the recommended dose. The PH have been mostly stable, a few fluctuations which have been corrected within 12h.

I got x2 260w QB led light boards. I have been testing different strengths and hight. Atm im running only 1 at half power 30cm above canopy as i was worried about light burn as i see curling leaves etc.
Ill post a bit of pictures and hope that you guys can help me identify my issues, its only my second grow.

New leaves grow out looking nice and dark green, after a while small spots and discoloration will happen and it will only worsen and worsen, oldest leaves are almost crispy now.

I will add that last time i did a res change, 5 days ago there was a lot of brown sludge in there, but i had a light leek so that migjtve been it, will check in next res change also.

I added a bunch of pictures, they are all the same plant but can be a week or two between pics
 

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jondamon

jondamon

Well-Known Member
What it looks like is a calcium problem.

The hard part is diagnosing what’s causing it.

did you sterilise your DWC res after you found The “sludge”?

what pH are you setting your DWC at?

What ppm and pH does your DWC read after 24hours of running?

with LED elevated levels of Ca and often Mg are required!

If you’re fresh mix is 700ppm and pH5.8 for example today at 8pm. What does it read tomorrow at 8pm after your plant has been using the mix for 24hours?
 
jondamon

jondamon

Well-Known Member
Also don’t be too quick to adjust your pH.

a fluctuation between 5.5-6.2 is good for the plants as different ions are available to the plant at different pH ranges so a swing within this range is perfect.
 
B

Bewi

Member
Hmm its barely feeding from what i can tell. In a 5 days it has gone down from 750ppm to 670ppm. First days the ph fluctate a bit by going up 0.2-0.5 and i ph it back down and ph have kept stabile last 3 days.

I was going to change res tomorrow, but i thimk i will do it today.

I didnt sterilize it, but i gave the tank a proper scrub with soap.

Thats the 4 time ive washed it since forst growth. Also had some sludge problems in the beginning, but that was different looking then what i had last. I will see later if its the same, i thought it might have been a light leak into the tank causing the sludge.

It is growing slow tho, this is a 2 fast 2 vast auto and according to the websites it should be finished in like 3-4 weeks.
 
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jondamon

jondamon

Well-Known Member
Bewi said:
Hmm its barely feeding from what i can tell. In a 5 days it has gone down from 750ppm to 670ppm. First days the ph fluctate a bit by going up 0.2-0.5 and i ph it back down and ph have kept stabile last 3 days.

I was going to change res tomorrow, but i thimk i will do it today.

I didnt sterilize it, but i gave the tank a proper scrub with soap.

Thats the 4 time ive washed it since forst growth. Also had some sludge problems in the beginning, but that was different looking then what i had last. I will see later if its the same, i thought it might have been a light leak into the tank causing the sludge.
Click to expand...
Have you got aeration in your tank?
 
jondamon

jondamon

Well-Known Member
Also.

a Rule of thumb.

don’t correct your res unless your ppm drops 150-200ppm or if the pH falls outside of 5.5-6.2.

you can correct too much and cause issues with uptake it too much correction is done using ph up/down etc.
 
B

Bewi

Member
I usually check the res 6-8h after i add so i can see how it is when fully mixed, and i correct. Then i check and correct once a day maybe if it needs.

But i will do once every 24h on next one.
Should i add in Cal-mag into that mix?
I havent used it so far
Also the GHE says in the feeding charts that i should have 1400ppm by now, but at 750 i started seeing small signs of nute burns, so maybe even go at around 550?

First growth i was never over 500ppm, caused trouble right away, but it was different nutrients
 
jondamon

jondamon

Well-Known Member
Bewi said:
I usually check the res 6-8h after i add so i can see how it is when fully mixed, and i correct. Then i check and correct once a day maybe if it needs.

But i will do once every 24h on next one.
Should i add in Cal-mag into that mix?
I havent used it so far
Click to expand...
I would add 150ppm of calmag and then your base nutes after that up to your current ppm.

the good Thing is that you’re getting a slight drop in ppm which means your feed solution is about where it needs to be.
 
B

Bewi

Member
jondamon said:
I would add 150ppm of calmag and then your base nutes after that up to your current ppm.

the good Thing is that you’re getting a slight drop in ppm which means your feed solution is about where it needs to be.
Click to expand...
Says 1,5-2ml per liter of water, should i follow that one or go by ppm? Cal-mag that is
 
jondamon

jondamon

Well-Known Member
Bewi said:
Says 1,5-2ml per liter of water, should i follow that one or go by ppm? Cal-mag that is
Click to expand...
Go by my ppm.

150ppm max to start with.

note any changes or whether the progression stops.

if it keeps happening then up it to 250ppm while keeping your top end ppms the same 700ppm.
 
jondamon

jondamon

Well-Known Member
Bewi said:
Also got any tips for the lights? Atm im using 1/6 of the power i have

Ok so add 150ppm of cal-mag, then add nutrients so it adds up to about 850-900ppm and keep a close eye?
Click to expand...
No.

add calmag 150ppm.

stir and make sure it’s mixed.

then add your trio up to 700ppm total.

150calmag + 550trio
 
B

Bewi

Member
Havent got much of a clue on calibrating the ppm meter, bought a bunch of cheap testers for ph and ppm, so if i suspect wrong i double check with a new one
 
jondamon

jondamon

Well-Known Member
Bewi said:
Havent got much of a clue on calibrating the ppm meter, bought a bunch of cheap testers for ph and ppm, so if i suspect wrong i double check with a new one
Click to expand...
Ah right ok so you’re not using digital ppm meter?
 
jondamon

jondamon

Well-Known Member
With a hydroponic grow I can’t stress enough the need to have a digital meter.

I use pH drops for testing ph and a BLUELAB EC truncheon for my nute strength but I use coco so it doesn’t need to be as exact on pH.
 
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