Bubble bucket ebb and flow system

Hello and help! I am new to hydro. Haven't grown in over 30 years and that was in backyard soil. I have a ebb and flow bubble bucket system. I am growing in the freezing northeast. I have a gorilla grow tent and diamond series 3w led light. Grew seedlings in rockwool 50/50 success. They are 12 days old and want to place in hydro with clay pebbles.

With this system I don't see how to keep the water an inch below the buckets since the ebb valve is higher than the bottom of the neti pot.

Do I just layer enough clay pebbles to keep the rockwool away from the bubbling water thru the rocks?

The rockwool is presently just sitting on the clay pebbles with bubbles around the edges but the rockwool was saturated with water. I believe this to be bad so I raised the cubes up on clay pebbles.

I have a heater in the tent circulating warm air 77-81 degrees with 44- 55% humidity .

Had light just with one switch on (blue) just switched both in this am as seedlings look sad

I will add pics later today. I am flummoxed with this whole process.

Thank you for any help and suggestions. I just can't figure out the rockwool water distance thing.

 

Thank you so much!