Slow growth and yellow leaves

[Marthajeep]

So I have two autos at week 4. (Rqs auto gorilla and Dreamberry) The first two weeks looked quite good. Then between the start of 3-4 showed very limited growth and the first two true leaves turned yellow, now I’m noticing the next set are doing the same. At first I thought it was a calmag issue and possibly nitrogen deficiency and immediately started adding it to my water which is ro, probably should have started that sooner. At day one of week 3 I started a half dose of roots uprising grow as a top dress. Now I feel like the top leaves are a bit dark leading me to think nitrogen toxicity, but with yellow leaves I’m at a loss. I started lst at week 3 so I could understand them being shorter, but around 4 inches is a bit ridiculous. I’m growing in ffof with nature’s living soil mixed into the bottom third of my 3 gal fabric pots. I water every 2-3 days as the soil is bone dry by then. I’ve been running at 75 degrees/ 55% rh. Not sure if my light could be a factor, Viparspectra va 1000, but I have an hlg 135 v2 arriving in two days. Any and all suggestions are welcome!

 

[GeorgeCloney]

Whats your soil and feed ph like?
Whats your EC or ppm feed?
Looks like the start of a phosphorus def'c.
But this comment means nothing until we know
the answer to my questions 1 &2....

 

[Mañ'O'Green]

They are indeed short for their age. They are showing some color which may indicate that it has been too cold? Is 75°F the day time temp and does it get colder at night?

You should not let the pot dry out. You may have "root pruned" the plant with dry pockets in the pots. When soil gets dry it can become hydrophobic and repels water. I would add a surfactant to your fertigation. I use yucca powder but you can use a couple of drops of liquid soap (NOT DETERGENT) if that is handy.

Why did you only mix the living soil in the bottom 1/3? it would be better to be mixed throughout. OF has a poor history here in the infirmary.

 

[Marthajeep]

75-78 lights on, 70 minimum lights out