Second Grow Stunts to zero at about week 3-4. Leaves yellow from the top down and curling

This is my second recent grow that looks like it's dying at three weeks. Probably at the development of leaf set six to seven.
Hydroponic grow. pH 5.7 to 6.3,, TDS 958,, water temp 67.5F. +/- 2.0F, relative humidity ~50%, fan ON low, light @75% of max.. 18on-6off, 16" above plant.
90% of water changed three days back with recommended amounts/gal Boost, Grow, MagiCal. I gotta be missing something

Your pH is too low. There's no fert burn from too much ferts because pH don't allow for ion exchange.

So 6.2 pH is too low ?? I thought that level allowed for most nutriments to be available for absorption.

In hydro your ph should be 5.5-5.9
Don't listen to someone if they don't grow hydro. They obviously don't know what they're talking about.
What kind of instrument are you using to measure ph? Cheap meters give bad readings.
You're in rockwool? How many times are you feeding per day and what style hydro are you running? Dwc?, dtw...etc...
Are you getting substantial runoff each watering event?
What kind of light/how many watts? 75% @ 16" with tiny plants is waaay to high imo
TDS @ 900+ is so high for small plants like that.
You also likely don't have to run calmag unless you're running ro, or your nutrients have lower calcium like maxi bloom. Too much calmag makes big problems. #1 new grower error. In all my time growing I've never used calmag, unless running ro, or when I used maxibloom but the amount you need to add is miniscule

Based on the first advice I began moving it up... currently 6.37, TDS=815. I'll start moving it back to the acid side. pH meter is one of those multiple measurement device.. sensor hangs down in my grow bucket. pH correlates well with a color indicator test I use for my swim spa. The rockwool plug is the little cube the seed sprouted in. It is currently suspended right above to at the water level. Air bubbles kick up enough spray to keep the plug moist. The roots have exited the wool fiber, but really haven't grown much either. Light is KIND LED X220 (220 watts max). Can drop TDS and pH with additional water adds. I am using RO water with Mg/Ca reintroduction.

PH now 5.65, TDS 434

That bitch might be dead at this point...
I can't explain why though...
Your PH is on point...
I mean, 700+ ppms is pretty high but that bitch is curling something crazy...

It cant be damping off...you stem looks like it was healthy.
I would try some botanicare liquid karma ...Only
see if she comes back around...

If she doesn't make it start over ...go with less ppms

Something doesn’t really add up here.. could you take a couple of snaps? One of the roots, one of your ph/ec meter and one of the tent from a couple of feet back for an overview?

DaveT said:

This is my second recent grow that looks like it's dying at three weeks. Probably at the development of leaf set six to seven.
Hydroponic grow. pH 5.7 to 6.3,, TDS 958,, water temp 67.5F. +/- 2.0F, relative humidity ~50%, fan ON low, light @75% of max.. 18on-6off, 16" above plant.
90% of water changed three days back with recommended amounts/gal Boost, Grow, MagiCal. I gotta be missing something

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That looks like it must of started of bad to begin with. Did you by any chance over wet in the first week or two or see any tiny flys at all ?
I have seen plants like that that will have tiny flys lay eggs ontop of the wet soil. These eggs go on to become tiny almost silvery transparent worms that burow into the roots and chew on them from they inside which causes hard thick knoted mutated root growth, aswell as them steeling all the nutients. This then cause them to grow very stunted and miniturized as well as looking very sick.
I cant see the the base and rockwool part of the plant clearly as the picture is abit blury in that part. But from what i can make out it does look like some roots are vissable that seem to look thick and kind of knoted. It could just be the photo. Is ther any way you can get a clear pic of the base of the plant as well as a pic of how the roots looks on the other side of your pot lid.

Overnight numbers settled to 6.05 pH, and 414 TDS... 1.0ml pH Down added... 5.30,,,445. pH will continue to creep... probably head back to 5.6 to5.7.
No soil was used in this grow. If soil born root maggots of some sort, I can examine under microscope.

an hour after adjusting pH 5.35 ,, 442 TDS. pH will probably stabilize at ~5.7 +/- 0.1

Air temps??

My guess is you are frying it with too much light with too cool air temp

It is dead. Mushy rotten roots and stem.

I think you pushed it too hard too early and just fried it - too much light and possibly too high ppms for this young stage.

MissinThe90’sStrains said:

I think you pushed it too hard too early and just fried it - too much light and possibly too high ppms for this young stage.

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Yup. Too wet mostly.

Light was ~30" above prior to lowering it. Air temp in chamber has been around 72F-77F.
Currently pH-5.68 @67.2F, 247-ORP, 432-TDS. Chamber 75.2F. 50% RH. Wool is saturated as I dropper water onto it as well as effervescence from the air bubbling into the water below.

did see this single tiny fly buzzing about

The method you chose is kinda difficult and there's a lot of room for error especially for someone new into the hobby.
You should be using larger rockwool cubes after roots show, like a 4x4.... And you should be soaking/buffering your cubes.... Or put hydroton in the basket.....
The water should have so much air going through it it should look like it's boiling if you're just using an air stone..... Personally I'd be running sprayers and an air stone.
You always hand water small plants in rockwool until roots really start to form. You should also be running sterile by adding pool shock, or hypochlorous acid.
What you're doing is obviously not working....
Maybe try coco dtw? It's still considered hydroponic growing, and it's far less likely to run into so many issues... Just a thought?
Might make it an easier stepping stone into a more complicated system like dwc.

Def a root rot problem. Don't reuse any stones or air lines. Bleach everything else. Add beneficial bacteria to your res. Recharge works great.

I've used rw and grown dwc for years, now I just use rw. You r probably keeping that cube to wet early on is all. And in turn you're letting some type of pathogen some type of bug. Some type of something get any type of foothold in your cube and then you go and you stick it in your reservoir and it stays soaked and the problem multiplies rapidly without any beneficial bacteria

Oh! That's why your plant is dead....you didn't do the dwc right...
I see now...
Don't go an buy the botanicare liquid karma...

Your plant is not even in the water...
I was wondering why you were failing...
Now I see. Why.