Which Machine Combo would be suitable for me if I plan to do a 15-20 minute EWOT session?

For an EWOT session of ~15-20 minutes at one stretch,  we recommend Combo A, which is the 10 LPM Machine-900L Bag combo or Combo B, which is the 5LPM machine- 900L Bag combo. For Combo B, you can fill the bag overnight and keep it ready for your session. This will save you some money on the machine, yet you'll be able to have a longer session.