To prevent root rot try the following steps to promote garden health:
Rinse and Refill the water bowl. This is good to do at-least once a month to replace old water filled with excess minerals left over from the liquid nutrients that the plants did not absorb. After refilling- add the recommended amount of liquid nutrients for your AeroGarden. OPTIONAL– add a teaspoon of food grade hydrogen peroxide to the water.
Mature plants will have an advanced root system that may overwhelm the water bowl of your garden. If the roots are healthy, then you will need to water more frequently due to the limited space in the water bowl and those thirsty roots.
To root trim or not? Some people do trim the roots of their mature plants BUT there is a high risk of over trimming and killing the plant. Because of this risk, it is not recommended.
So take a look under the grow deck and do a Garden Check Up on your roots.