Very cool to see them 3 all together and all around the same speed and size. The one with the ripples on the leafs a bit looks like a bit of calmag deficiency to me. I get it all the time at seedling phase dice they can't handle a high ppm and the coco grabs the calmag first. I do a weak foliar spray and that seems to pull them right out of it. But I'm over cautious and could be wrong. They look good.
Yeah, I think it's easy to get too twitchy about possible deficiencies or 'lock out'. I'm guessing it's mostly false alarms, so I keep everything super simple so I have minimal variables, which is another reason I want to try 5 different strains in the same reservoir to see for myself how sensitive they all are to the same nutrient. So far none of them are complaining about 500ppm. I am a little concerned about the slenderness of the stems at this stage though.
My Auto Glueberry OG

... I ain't scared. Call in the banners!
Tough talk at this early stage, let's see if you need your brown trousers by the time the international judges fly in for the presentation ;¬)