First timer with shriveling, curling leaves.. HELP PLEASE!

Hey folks! Im a grow newbie that decided to do it just to see if i could. My plants are almost 2 months old and EVERYTHING was going lovely intil i transplanted and now i notice one of my kids is displaying some issues. I KNOW im not doing EVERYTHING i should to grow perfect plants. Heres my troubleshooting form and a few pics. Hopefully, someone can offer a quick easy fix for my issue. Thanks in advance!

What is your experience level? (first timer, novice, experienced...)

Your Equipment:
.1) Type and wattage of lights. Energy saver fluorescents
.2) Distance from tops? 6"
.3) Reflector type? bare bulb
.4) Is there a consistent fresh air supply? YES
.5) Do you have an exhaust fan and a circulation fan? YES
.6) What are the bulb wattages, kelvin ratings, and schedule? Four 75 watts.. 24 hours

Your medium:
.7) Specific brand and type of soil: Miracle Grow potting soil
.8) Size of container. 5 Gal buckets
.9) Did you use peat pucks (or similar): Jiffy pots

Your nutrients and water:
10) Source of water? 7.0 filtered tap
11) Method of checking water ph. test strips
12) Method of adjusting water ph. NONE YET
13) Specific brand and N-P-K ratio for each bottle.
14) How often are you watering between feedings, and how much per watering? Every 3 days; half a gallon
15) Any additives or tea's? NO
16) Are your ph levels stable, or do they fluctuate? Unknown as of now
17) What is your ingoing water's ph? ...your runoff ph? Ingoing=7.0, runoff=6.7
18) Do you foliar feed? NO

Your growroom:
19) Indoors
20) What size of closet:5x4"
21) What are the temps and humidity levels while lights are on? ...With lights off? Temp is about 78F (I live above a bakery!)
22) Have you seen signs of insects in the growroom? NONE

Your strain:
23) What strain are you growing? Indica dominate
24) From seeds or clones? Seeds
25) Is this an autoflower strain? Unknown

PS: I flushed ALL my buckets with 3 gal of water yesterday after noticing the problem and this is the Only 1 out of 5 that is experiencing the issue

Again, thanks for any input!

there not curling they are just droopy. Do you water them everyday ? If so, you shouldnt ,wait till the soil drys out, plants dont like too much water. Also maybe its very hot ? heat can cause leaves to droop or extreme cold.

Curious...why no shots of the whole plant? How many plants do you have in each pot?

Depending on the perlite content, (or lack of perlite) a 5 gallon bucket will retain water like crazy. You do have drainage holes in the bottom, right? When you water, do you water slowly, or just splash it in? Does the water flow immediatelly out of the bottom? Does any absorb into the medium?

During the hot dry months, I have to water my 5 gallon buckets with 1/4 to 1/2 gallon daily. But I do use extra perlite to avoid oversaturation.

6" is too far, get 'em closer, or add more lights, or think about an HID system. (metal halide or HPS)

Why no nutrients yet?

Whatever size container you are in...always keep soil to within an inch or two of the top. The top of the rootball needs air circulation too. Just be sure to leave enough room for watering.

Whatever is going on these plants need a LOT more light...