Here is a test video of a single pot 27L DWC with a 21cm air stone.
https://www.youtube.com/watch?v=DA6NOA53WvE
Here is the DWC;
https://www.ebay.com.au/itm/16L-27L...RE-INDOOR-PLANT/283061939959?var=583454353860
Here is the air stone;
https://www.ebay.com.au/itm/21CM-Ai...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
Here is the air pump;
https://www.ebay.com.au/itm/220V-38...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
That should aerate the entire root ball to the max.
https://www.youtube.com/watch?v=DA6NOA53WvE
Here is the DWC;
https://www.ebay.com.au/itm/16L-27L...RE-INDOOR-PLANT/283061939959?var=583454353860
Here is the air stone;
https://www.ebay.com.au/itm/21CM-Ai...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
Here is the air pump;
https://www.ebay.com.au/itm/220V-38...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
That should aerate the entire root ball to the max.