Whats the closest you can grow plants together in a dwc system

Curious because i got a set up and the holes seem to close for me..

They can be just 3 or 4 inches apart. As they get taller, they will crowd each other out. It depends on if youa re doing a SOG, and if you are starting with seed, sprouts, clones, or feminized seed. I use a tank with 6 holes, with only about 1 and half inches separating them, and I've gotten plants 4 ft tall in it. Look at the link to my pics under my signature on this post.
AND, if you start with unsexed plants, you will thin half of them out, when you toss the males. don't let it worry you, just do it!