What is happening?!

[420EVANSTON]

What is causing this on my Zkettles Berry Blast.
Ph or nutrient deficiency?
Last week I awoke and found one of my babies not doing too well. Brown spots developed overnight. Then again days later on a new set of leaves.
– tap water pH at 6
– water when dry a couple inches
– Spider Farm SF-2000 hung at recommended 24”
– organic soil with perlite
– no added nutrients
– light on 20/4
– humidity at 50-60%
– temp at 75-80 degrees
Suggestions would be greatly appreciated!

12 Days

18 Days (same plant)

18 Days (different Zkittle)
Droopy leaves no brown spots

 

[namvet25]

I would raise ph closer to 6.5 and shorten lights on a little. Don't forget to water entire pot because roots are growing fast at this stage.

 

[Waira]

What soil brand is this? It looks to be kinda iffy, a lot of wood bits, clumps, too much perlite, poorly cooked.... My guess at this early stage, there's something bad with the soil, off pH, or something else,... No nutes by 18 days is another reason they are small, and at this age, possible defc.'s are suspect as well... Start weak nutes by end of first week, sooner if it very mild soil... Inoculants and very helpful, so are enzymes....

The soil should always be tested for pH before anything, but too late for that now...Off pH locks out nutes, harms roots potentially, soil life hates it too. You will need a good soil pH probe (wrongly called a meter sometimes; meters are for liquids only)... the Accurate 8 (CPW) is a good unit for in-pot pH testing. Run-off pH testing is not a good method, dubious accuracy....

It's late in the game now for auto's, day 18, sexing is likely to happen soon; they are unlikely to get much size to them, but you can try....
Do you have a pH meter? Calibrated recently, never dried out stored in the proper solution? If not, it's accuracy will be suspect too...
Let us know, maybe you can do a slurry test of the soil out of the bag and see if it started out bad to begin with.
1/2c soil, 1/2c low ppm water (RO/Di/spring-drinking)... mix, let sit for 20 min., drain off liquid and test...