Trying DWC hydro for the first time. One plant has possible deficiency/issue

[Space Goblin]

3 out of 4 plants are already growing WAY faster than anything I've managed to grow in soil, but one of them is off to a rough start. I'm doing 2 photoperiod plants and 2 autoflowers. They just passed their first week.

The 420 Fastbuds Smoothie autoflower is showing some problems. The roots are starting to come out of the bottom of the net pot, and are nice and white. The water is 72 degrees, the ph is 6.00, and the ppm is 170. I'm using Cultured Solutions nutrients, which are designed for hydro and I'm within all the parameters listed in the feeding schedule.

I'm going to Make some white covers for the tops of the buckets so they don't absorb as much heat from the light, so maybe I can get the temperature down a couple of degrees. But I have a feeling that the issue(s) the plant is exhibiting have to do with something other than temperature.

Any ideas?

 

[Waira]

Hmmm, weird reaction she's having when the others are OK,... it looks like what happens when there's a temporary but significant pH drift... Aqueous availability is a bit of a bitch to manage, small drift can cause problems sometimes...
I'm thinking the 170ppm is low even for this stage,... (all nutes? no base water ppm?).... has this plant been iffy from the start? Could be that it's just a lousy plant, all seeds are a little gamble after all!