Combo Problem

Okay, so I have some plants in a wilma set up, c. 4 weeks old. I've just switched to HPS as they all weren't getting enough light from the small CFL i had. So I'm wandering what you guys think of these unhappy looking plants? (there is definitely some heat stress when I failed to position the lights properly) But there is drooping and leaf splitting and general unhappiness? I have read the info but I'm unsure if this is due to over watering or what?
ph is 6.1, ec is 1.8-2.0 (background EC 0.6), 400w hps, 20 on /4 off
if anyone has any advice or ideas they would be more than welcome.

1. Coco pH is 5.8, most hydro... 5.5 to 6.0.
2. Organics/Soil pH is 6.5, but ranges up to 7.0.

You are not running 5.8 or 6.5. I cannot understand why you would run 6.1, especially in what appears to be coco, when it is not in either range... Where did you get that idea from?

Plant's look typically short on Potassium as in most coco grows that utilize Canna Coco A+B. This coincides with the heat stress.

Also, for the size of the plants your EC is too high. Aim for 1.5 until you hit week 3 of flowering then you can move it up to 1.9ish until week 6-7, then drop it down to 1.1 for a week or two before running straight water for the last 10 days or so.

Looks like the medium is too dry. Does each pot have the one outlet? If so you could attach a ring dripper and get better results.