Deficiency, magnesium? In living soil Sohum/Autopots

[squarewaves]

Hi, I have 2 x 5 gallon springpots in XL trays, healthy solo cup transplant to Sohum water only soil. 9 days top watering, healthy plants, switched on system. Plants seemed to do really well until the OMG started to show a leaf deficiency. All fan leaves died and I had to trim them off. The smaller growth is now picking up but its super stunted.

The other plant was much healthier ... grew really well ... about 5 days ago a similar leaf deficiency started. I'm worried I'm going to lose this plant as well.

Ppfd is totally in line, around 300 at the canopy. Temp 80/81F, RH 50- 60, vpd is in order. Good air circulation and fresh air pulling in 24/7.

PH in the trays is about 6.7, res climbed to high 6s, but its tested daily and kept around 6.25. In the res all I have is SLF-100 to support plant immunity and keep the lines clean, and CX regenaroot, suggested to me by Autopots directly for root health (its an auxin precursor).

I'm attaching pics. Curious if anyone had any sense of whats going wrong. I even called HLG to see if Im burning my plants with a bad lux to ppfd conversion but apparently I'm spot on.

If you check the last pic you'll see my sad OMG plant ... its struggling with the inner growth, all but 2 fan leaves had to be removed as they were more than 50% dead.

One issue I'm noticing, but this is my first AP grow ... is that the soil is bone dry down as far as I can push my fingers down the side of the pot. Thats got to be about 4 inches. I have 1" of #3 perlite at the bottom as instructed. Airdomes are on. Should this much of the soil be dry? I was expecting the soil to wick moisture to the top.or at least close to. Perhaps the severe dryness is causing a ph spike in the soil In not seeing in the tray? I really have no good guess here.

Any thoughts? Thank you.

 

[013]

I know autopots are a thing but I’m having trouble understanding their use in veg cycle. I can understand it perhaps in flower mode but not in veg.…

One more thing that caught my eye was the 9 days of top watering?? Sure maybe for hydro users to tease the roots to grow down into the reservoir, but I’m having a hard time envisioning an indoor…..soil grown..….veg plant that needs water 9 days in a row.

The bottom layer of perlite actually raises or perches the water table even higher. We have moved beyond sticking a finger in the soil….. lift the pot method or weigh the pot are more accurate. Take same size container and fill it with exactly the same soil mix but do not water it in. Place the container of dry soil on a scale and take reading….. now compare weight with existing container, the plant weighs nothing but the difference will be the water weight….

Airdomes? Domes are for clones to keep rh high while new cuttings develops roots, but domes are not needed for veg plants. Inside a dome there is not much need for a plant to transpire which means the plant drinks even less water. Piss poor analogy but would you rather have an infant that needed an incubator to survive? Or an infant that had no need of an incubator??

I suspect what is going on is….. even tho the soil feels dry to you I’m thinking that lack of oxygen to the root zone is the problem. Roots cannot breathe in a continuously wet soil… I know this above prolly sounds harsh but that’s never my intention. My 2 cents but please see what else comes in…..

Welcome aboard squarewaves!

 

[Sueet]

Other than what @013 said I would add that you want to be aiming at 6.3 pH for a soil grow. Also, when dealing with a problem, don't remove the leaves until they are fully dead or yellow. The plant can still retrieve stored nutrients out of the leaf while it is still attached/alive, and also it could cause the plant to just start taking from the next leaf up.