Now I see your question about the water level:::

Well, thinking about it more, in your setup, you might, or might not have some water level under the roots.

SCENARIO A:::
You've got your tub, with your clones on top... and your fogger heads under the roots. So yeah, you have some water level under there, so the heads can produce the fog.

SCENARIO B:::
You've got your tub, with your clones on top... you've built a fog "chamber" in which fog will get produced, then pumped... in this setup, no, your roots wouldn't have water under them.

But yes, the heads need a certain level to work... if not, they fail... but the FutureGarden heads have an super cool automatic shut-off... you can see it in the pictures... you see the head? You see that it has kind of a black "bridge" on top of the chrome thing?

Well, that's the water level sensor. If the water level is under that "bridge", the fogger head doesn't turn ON.

Best,

-turtle420
.