Right idea but just a couple of suggestions.
1. Need to use a tupperware bottom that doesn't allow light into the roots or water - reason is is that this will promote growth of unwanted things in the water tub.
2. The rockwool cubs cant be submerged in the water - reason is that rockwool cubes can absorb a lot of water and hold it for long periods of time. Basicaly you are drowning the clone in this set up.
for this set up you could
a. Use a foam plug that dangels the end of your clone in the water
or
b. Water rockwool by hand 1 time a day just barly untill you see roots out the bottom the dangle the roots in your setup but not alowing the water to touch the rockwool.
c. Get 3" net pots fill 1/3 with hydrotron beads place rockwool cube in and then fill in spots with the hydrotron beads and water once a day lightly untill you see roots coming out the bottom then stick it in your setup.
anyway you do it the moral of the story is that right now you are drowning the clones by not alowing the rockwool to dry and provide oxygen to the cuttlings hence drowning them.
This is just my opinion. Rockwool isnt the easiest to clone with if you are not familiar with it.
Personaly I do a 3 step process that for me has been fool proof so far at a 100% success rate.
First I start with these that you can buy at home depot
Place cuttling in and hand water for 1 week once a day in the litte dome thing it comes with.
Then cut the netting and place the roots under the sink to wash away the dirt.
take a 1.5" rockwool cube and cut on one side verticaly to the center so its like a "packman" just dont cut any of it out. This is when it is wet.
Place cutling with the new roots in this and then do the netting post and hydrotron thing as mentioned above. Hand water until roots break through the bottom of the rockwool.
Then place in my set up which is a bubbler just like yours ( except with a non clear bottom )
This is just my setup and my opinion. I would like to hear others opinions as mine is just one way.