Question about DWC, should the pots touch the water?

Well in my friends setup his pots touch the water, I've been looking around online and now I've noticed other peoples setups and it looks like the water level is below the pots and the roots grow out into the water.

Is it wrong to have the water level touching or a 1/4 of an inch above the bottom of the pots? Or should it be dropped below the pots?

Each plant is in a rockwool cube, but to keep them from moving around my friend has hydraton(forgot how it was spelt) rocks around the rockwool cubes.

The pots shouldn't be touching the water. The water level should be just high enough that when the air bubbles pop they send micro droplets of nutrient up to the roots. As the plants get older the roots can grow down into the water but they still need much of their surface able to breathe above the water. My pots sit about 6 to 8 inches out of the water. Without the sprayers running, there is still nutrient that drips off the bottom of the pots just from the air bubbles. Good luck

Grow Strong