Yellowing veins and spots on older leaves?

[Creep420]

Hello everyone.
I am on my second grow, So I am still pretty new to growing and diagnosing issues. I have looked at similar questions asked here and on other forums and finding multiple diagnosis.
When I first started these seedlings out, I overwatered them a bit and am hoping this is residual backlash. At that time about 2 weeks ago, they were in rough shape from the overwatering, showing yellowing leaves, and overall bad health. Once I let them dry and watered them correctly, new growth came in nicely.

I have noticed one of the plants has been showing yellow spotting along the veins of the older leaves, Along with some slight brown discoloration. The serrations on the sides of a couple leaves were also bent upwards and causing the “taco” effect. (I just lowered the temps to hopefully remedy this)
They were moved from a T5 40W starter grow light into the tent under 400W Mh on Weds. Also would like to note, it is only happening to one of my plants, however there is one other that is getting the serrations of the leaves turning up as well. The others all look like they are progressing normally

- Using 400W MH about 30” from the canopy
-Temp is 75 degrees F .(It was 80 but made it cooler earlier today)
-Plants are about 5 weeks old
-There is an Exhaust Duct fan, and one fan under the light and one fan going across the top of the canopy lightly.
-Using Happy Frog soil, with 1/3 extra perlite.
-Transplanted from seedling cups on Wednesday to 1Gal pots with extra holes for drainage.
-I now water roughly every 5 days when soil is dry with Deer Park water with a Ph of 6.3.
-No nutes added as we are using new soil

Any help is greatly appreciated, thank you all in advance.

 

[Creep420]

Here is a photo of the overall plant after watering

 

[m8ty]

Too much light, raise the light so it's 4 feet from the floor, 400 watts four feet up is 100 watts at the floor. 100 watts is all that tiny plant needs, why go from 50 Watts T5 to a 400 watt HID ?? First you were killing it with too much water and now you're killing it with too much light. Top three ways to kill your plants: too much light too many nutrients and over watering.

 

[Creep420]

I can do that. Do you think it’s the light causing stress?

 

[Creep420]

Understood. I wasn’t sure if they could use better light at this size. I could also turn the wattage down to 200w if you think that will help.
The reason why I I did the switch was I did this on my last grow, but kept them under 200W during the early stages and turned it up as they grew larger. So I’m guessing that was the better way to go about it.
Im still learning as it is my 2nd grow

 

[MIMedGrower]

With nutes and light its best to ease them into it. Moving the light a little closer each day and watching to see if leaves are flat and happy or curled, edgy and stressed. Also sometimes they point up hard but still mostly flat if the light is a bit to intense. Easy to tell if they improve backed off and inch or two.

 

[Creep420]

Okay I got you. So it probably shocked them a bit just throwing them into a new stronger setting. I will ease the light up a few inches to see it it helps them transition into things.

 

[MIMedGrower]

Okay I got you. So it probably shocked them a bit just throwing them into a new stronger setting. I will ease the light up a few inches to see it it helps them transition into things.

3-4’ from the top of the plants like said above. I was talking about finer adjustments when the plants are generally happy.

 

[Creep420]

I will do that. Small increments at a time when I need to change things. That way I can ease back if I notice they aren’t adapting to the changes right off and not much damage is done. I’ll do that with nutes as well when the time comes. Appreciate the help. You gave me sound advice on my question weeks back, thank you again.