Deficiency/toxicity? - Tha Shiznit Autoflower

yeatster said:

My understanding is that the mix of perlite and biobizz light would be very light in fertilizer.
How could there be a toxicity?
The dark green sure looks like N toxicity to me.
But the discolored leaf looks to be a deficiency.
I am confused with this and really hope there to be a confirmation.

Me, personally, I would give it a feed of 1/4 strenth nutes, hoping it stopped the discoloring of the leaves.
He has been giving it straight water, no nutes, and says it is progressing.

????

Edit: symptoms are "progressing"

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Hey man.

Yeah, syptoms are slightly worse in 24 hours. Plant is still growing pretty well otherwise. My worry was that if it's nitrogen toxic, and potassium deficient, how do I balance one without killing it with extra nitrogen. Just give it a banana? That's potassium right? Haha.

I'll see how she grows in 24-48 hours, then decide whether to nute or not. Thanks man, good looking out.

JohnySmith1 said:

No, perlite do not dilute the concentration of fertilizers in the mix, all it does is reduces the surface area. It means there fewer fertilizers according to weight but they released and absorbed at the same rate (1.2 EC).

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Okay, I understand that, and please don't take this as being argumentative, you clearly know what you're talking about. I am just trying to understand a tad better.

If I add 30% perlite I understand it won't change the concentration of the mix but...
If I am soaking, say, I liter of said mix, with water, won't there technically be less fertilizer being absorbed because of the pelite?
Or, does perlite not hold any water?

Sorry for being a bug.
Peace

I don't take it as an argument. If you are interested, I am happy to explain.
Perlite do not have the property to absorb nutrients and slowly release like soil, which means nutrients are not distributed equally in the mix. So roots that are touching soil absorbing fertilizers at the rate 1.2 EC and roots that are touching perlite absorbing oxygen. (For this reason, hydroponic systems must be watered 3 times a day for sufficient nutrient absorbtion). So regardless of perlite to soil ratio absorption of ferts will be at the same rate but oxygen will be increased.

JohnySmith1 said:

I don't take it as an argument. If you are interested, I am happy to explain.
Perlite do not have the property to absorb nutrients and slowly release like soil, which means nutrients are not distributed equally in the mix. So roots that are touching soil absorbing fertilizers at the rate 1.2 EC and roots that are touching perlite absorbing oxygen. (For this reason, hydroponic systems must be watered 3 times a day for sufficient nutrient absorbtion). So regardless of perlite to soil ratio absorption of ferts will be at the same rate but oxygen will be increased.

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Gotcha!
Thanks for clearing that up.
Peace

yeatster said:

Gotcha!
Thanks for clearing that up.
Peace

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Glad to be helpful)

I would venture that the rest of the plant looks on point so just feeding tap water for a bit should suffice. Water enough to get run off and with your new meter feel it out. She'll adjust. Seedlings have a little issues all the time. Let her go another week or so and remove affected leaf. So that you have finite control over this in the future start with rapid rooters or rockwool. Get her past preveg then pop her into the biobizz mix you have. I know some folks don't like upcanning; however, there is a postive stress that goes with the process that is can be attributed to overall plant toughness having to transcend different pot sizes till it gets to the final destination. Just like a woman you have to treat her a little rough to get what you want. So plan B. I she is indeed getting worse move her into some uncharged coir for a bit as your root structure shouldn't be all that unmanagable at this point.