airstones are not really necessary in waterfarms. this is heavily debated, but, please be assured, no airstones are necessary, for tru. 12 grows in waterfarms, 100% success. one good air stone/disc in the res is a good option, but none are needed in the individual buckets. here's the deal:
waterfarms are top fed, airstone oxegenation is important when roots are IN the nute soultion/water, DWC etc...
you don't want to have too much root growth thru the holes in the upper bucket, you should trim them back occasionally. airstones are needed with those huge root systems that fill out the botton of the bucket, usually this happens because the roots grow in search water/nutes as the pump cycle is not adequate to provide all they need in the drip circulation. i've always run the drippers 24/7 during vege then off when the lights go out during flowering. this is one of the main points to hyroponics, small root systems for large plants. i live in a pretty dry climate and always have great ventilation. alternatively, i've seen folks stop using the drippers after letting the roots grow into the nute solution and adding airstones, huge rootmass insues. this becomes a DWC, which has a host of potential problems i'd rather not introduce. just letting yous know what i've experienced. different strokes for different folks. i've done great with my methodology, yielding nearly an lb. per plant average. purple kush, grapefruit indica, and somango are my mainstays. sour D and trinity are my latest sojourns strainwise.
steady rock easy, all the while keeping the man down.
bless,
-g