you dont even need to bubble it. just let it sit out. it only takes about 20 minutes. however it is better to bubble because it oxygenates water which the plants roots just love.
i actually think thats why hydro is faster, much more oxygen to the roots. also the ph is much easier to stabilize.
also i've grown with water straight out of the tap without letting it sit out. it never seemed to harm anything but i still let it evaporate anyway.