I would use one of these
http://www.drsfostersmith.com/Produc...&N=2004+113405

They improve the oxygen levels instead of having co2 buildups.
If you have a big container and need more oxygen for your roots you can take a sponge and a rubberband or hot glue. Hot glue it to the back of the airstone so it floats instead of being at the bottom.
And maybe put the nutes in the sponge so the arent all over this will increase the plants growth.

Depending on if the nutes are heavier than the water.
If they are then I would pour them in at the water line and turn up your air pump.

Look for ones that have less co2 buildup co2 will kill ur roots.