First grow Sick seedling need help

[Scowlion]

Hey, this gal is 10 days old and the past two days she’s been showing these signs of the leaves curling down with “rusty” brown spots.

Current set-up:

4x102L tubs, 4 plants in each

6x12inch airstones- 950 gph air pump(for each tub)

ph constant at 5.6 water temps 74F

Room temp-84F 75% humidity

Nutes: 160ml Rhizotonic, 25ml AN Micro, bloom, grow (75ml total), 25ml cal mag (for each tub)

440ppm total

960w QB LEDs

There’s no root rot.

She’s the only girl in her tub showing these problems, I’ve looked online and it seems she may have a cal-mag or phosphorus issue. Thought I should get a second opinion To make sure.
Pics:

 

[Bigg Al]

I think you should raise your ph to 5.8-6.2. Plants that nutes at different ph levels. Yours might be a little low. Just my 2 cents.

 

[AutoWonders]

I think you should raise your ph to 5.8-6.2. Plants that nutes at different ph levels. Yours might be a little low. Just my 2 cents.

I'm inclined to agree. 5.6 is the low end. There is no wiggle room on the low end.

 

[HonestGR]

Fluxuate you pH slightly. (Up)