HELP Leaves yellow spots and shriviling w/Pics

My plants are showings signs of 2 problems, they may be related or not?

MY INFO
32 days since germination
Watering with soak and let dry method, and have just started to bring down the pH to 6.0 (with last watering), NO NUTRUIENTS USED YET
Using 400 watt mh Sun System1, keeping light about 2 1/2 feet above tops, dererminded this distance by heat on hand (had it closer first day)
Changed from Floresents to Metal Hal (3 days ago)
18 hours daylight, 6 hours dark
Temp is 87 and Humidity 56%
first pot size was 8oz cups, then 1/2 gal (as shown) The 8oz cups were Mircale Gro .21-.07-.14, then transplanted into 1/2 gal and used Fox Farm, Ocean Forest Potting Soil (3 days ago)
Pruned after 3rd set of leaves (2 weeks ago)


MY PROBLEMS
1.First full set of leaves are now showing signs of yellw spots on 50% of the plants.

2.Leaves are shriveling up and getting brittle starting at the tips and working back, this is happening AFTER Changing to MH from Flor., but before the transplanting by a day or so. This is affecting old and new growth.

WHAT I HAVE DONE
1. Raise light
2. Keeping temp pretty stedy at 87 day, 70 night
3. Watering with only water, and really flushed and let them drain yesterday.

Thanks to anyone with advice this is my 1st attempt

FEED THEM!

The speckles look like flying insect damage. Yellow sticky traps are excellent.

pH 6.0 is a touch low for soil. The dark, brittle leaf damage is consistent with that. Go back to 6.5.

In the future, avoid transplanting when your plants are already showing signs of stress unless you know you have to get them out of the old pot FAST for some reason (bad dirt, rootbound).