Please help diagnose problem

Doesn't look like toxicity. Your lower leaves look like N deficient. Yellowing.
400ppm is too low.

Tap water starts at 200 and you end up at 400-600 which means your feed is only 200-400 ppm. Low in my opinion. Like DR WHO described, they look hungry or micro deficient. It's depleting them fast.

Is your water hard water? well water? municipal?
There might be something in the water throwing off the balance. Not likely unless you're on well water.

Some strains just eat more and grow faster.

TheHarvester said:

Doesn't look like toxicity. Your lower leaves look like N deficient. Yellowing.
400ppm is too low.

Tap water starts at 200 and you end up at 400-600 which means your feed is only 200-400 ppm. Low in my opinion. Like DR WHO described, they look hungry or micro deficient. It's depleting them fast.

Is your water hard water? well water? municipal?
There might be something in the water throwing off the balance. Not likely unless you're on well water.

Some strains just eat more and grow faster.

Click to expand...

Thanks for your reply. I was wondering how you would explain the major clawing and the yellow tips ?

My water is really hard

Hard water was my first thought. If there's calcium/magnesium in your water and your feed. It might be left behind while the other nutrients are being taken up which would cause your pH to rise.
Second that can simple cause and imbalance and lock out another element.

Your water is probably higher in pH to start then right?? Do you need to use PH up or down?

Clawing isn't always toxicity in my mind.

This is the toxicity claw.

Yours is micro deficiency/pH related I think.
Your leaves are droopy down near the lower part of the plant, sign of malnutrition. The cells can't function like they are suppose to.

TheHarvester said:

Hard water was my first thought. If there's calcium/magnesium in your water and your feed. It might be left behind while the other nutrients are being taken up which would cause your pH to rise.
Second that can simple cause and imbalance and lock out another element.

Your water is probably higher in pH to start then right?? Do you need to use PH up or down?

Clawing isn't always toxicity in my mind.

This is the toxicity claw.

Yours is micro deficiency/pH related I think.
Your leaves are droopy down near the lower part of the plant, sign of malnutrition. The cells can't function like they are suppose to.

Click to expand...

Yes that's correct. My ph is around 7.8 at the tap.

Sorry I just want to confirm we are talking about the same pictures. The original pictures are from a while ago. The toxicity photos I am talking about is from about 6 posts back.

We are talking about the same pictures. I know the claw makes you think toxicity but with those lower ppm numbers and your other plant not being affected I can't see it being that.
Plus it just looks more like a pH/micro deficiency to me.

If you had it at 600-700ppm with the first pictures right? and they were deficient. So with a bigger plant it's going to take a higher ppm to satisfy it.

Also after you take off your starting ppm you aren't left with much nutrient in your solution. only 500ppm. That's a standard level feed to clones and small seedlings. A plant that size would need more. Not always, some are more hungry then other.
This means your micros are really low and get used up quick leaving it deficient. On top of your hard water which will make your pH buffer up, which isn't good for you if you are staring at 6.0
i'd start down at 5.6-5.8 so it can't buffer too high.

After a couple days when you pH is it higher or lower then when you put it in?