Potassium issue?

These are on day 27 from sprout. Being grown currently in 1 gallon pots of 75% Fox Farms Happy Frog / 25% Perlite. Temps are 27c/80 with 60-65 RH in the day and 20c/68f 60-65 RH at night. They were given tap water left out for 24 hrs(around 300 ppm ph'ed to 6.5) since spout and a bacterial product called Miicrobial Mass every two weeks until 5 days ago when i fed them the first time. I fed them what is suggest for seedlings in the Greenleaf Mega Crop line. i.e. Mega Crop, Sea-K Kelp Extract and Sweet Candy and it came out around 600 ppm. The next watering after that was straight water and that's where i'm at now. I've always ph'ed to 6.5 and I water until at least 20% runoff and wait until they are completely dry(3-5 days). My lights are led qb's roughly 20-24 inches from the plants at 23k lux.

To me the plants appear overwatered which could contribute to lockouts and root issues.
even in 1 gallon with FFOF you shouldn't have needed nutes up to this point either, although soon
FFOF isn't like watering in pure coco and I would never water to 20 percent runoff in it this early personally.
I would probably up pot to help them dry out get some fresh soil around them.

Like dbz said, why are you feeding it, FF OF has plenty of nutrients in it to feed that plant until it would have outgrew that 1 gallon pot. Really the only thing I ever give a seedling being grown in FF OF/HF is a supplement of camg+ @ 1/2 tsp per gallon starting from day 14 because FF doesn't put enough ca/mg in their mixes. And that is all they get through their entire up-potting to their final pot. And I only begin to feed a plant around the 3 week of flower, and that's after vegging them for 8 weeks. My up-pot scheduled goes like this... pop the seed in a solo cup, keep it in there for 21 days and just water it, but start adding a camg+ supplement to the water after 14 days, then I up-pot it to a 1 gallon pot, and I leave it in there for 21 days and I just water it with a camg+ supplement added, then I up-pot it to my final pot, which is either a 4-5 gallon pot, and I just water it with a camg+ supplement for 14 days, then I flip it, and continue with just watering it with a camg+ supplement for 14 more days, and then and only then do I begin to feed it!