Do not use warm or hot liquids with the Aerflo System.
Warm or hot liquids will heat up the carbonating capsule inside of the Aerflo system. Although it takes very high temperatures before it can cause damage to the capsules, we highly recommend avoid heat at all costs.
The colder the water, the better. Cold water helps with carbonation efficiency (so you will get more sparkling water out of 1x Capsule), and it tastes better.