Root development on seedling

Is it normal to only have the tap root after 5-6 days of being in bubble system? Like there isn't any branching off going on. These aren't clones, just little seedlings.Thanks!

Probably normal but what is your PPM and pH?

I use an aero type cloner. A week seems to be about average to show, then the roots really start to take off.

Ph 5.8 and ppm 180. The ppm has been 20 ish but I had a rising ph issue so I re did the setup to ensure light proof and put in a tiny bit of dyna grow and protekt to help stabilize ph. The cotelydon are curled but I see new growth on the new leaves each day and they look healthy. The stems are kinda dark purplish but I don't see that being a big deal at this age

I've tried the aero cloner before but didn't like it. I was using a 396 gph pump in a 5 gal bucket with 8 360 sprayers and the pump kept heating up the water.