The Squid
Spaced-out CephaloMOD
A lot can happen in three days of growth. Several inches of growth is possible. Plus, you're gonna have different phenotypes of that strain and they don't all grow the same. That one branching out looks like it might be a little bushier, the other more tall, but who knows. In three days that first one could easily look like the second in good light and conditions. I wouldn't worry about it they are green and healthy.
Are you checking the ph of your runoff? If so, what is it?
Are you checking the ph of your runoff? If so, what is it?