Outdoor - orange/brown spots developing

I've got clones growing outdoors that are all starting to show orange/brown spotting developing in the veins of the leaves, and then consume most of the leaf before it curls and dies. This is affecting 4 of my 8 plants. Any ideas?

Soil Growers:
1. Clones
2. 2 months
3. 12 inches
4. 7 gallon smartpots
5. FFOF+perlite
6. Watering when dry; tap water
7. ?
8. Grow big, big bloom
9. No
10. Outdoor
11. N/A
12. N/A
13. ~70 degrees F
14. ?
15. No
16. 3 indoor grows, 1 outdoor season.

Looks like calcium Mr Slacks; a sprinkling of dolomite over soil surface or use a product from hydro shop called CalMag. Mg deficiency is also there with bronzed, dried and slightly distorted leaves.

Tapwater's pH is generally out and it contains purifying chemicals like chlorine that can cause discolouration of leaves. Run it through a filter water purifier, or at least let it stand in container for 24 hours to let chlorine dissipate. Try and source some rain or RO water, or like i do, a clean creek. lol nigel