Looks like slight overwatering.
The larger the container, the more difficult it becomes to regulate the moisture. Since cannabis prefers a wet/dry cycle, perhaps skip a day between waterings.
Rusty Trichome Reviewed by Rusty Trichome on . Crispy leaf tips, what could this be? Ok, well my first grow went well without this issue, but since I transplanted and put under HPS lighting I noticed the leaf tip on this plant looks like it is dying, otherwise the plant is doing great. When I transplanted I did get rid of the old soil off the roots, not sure if this could have done anything. Conditions: Watering once a day (not alot of water) HPS light 17 inches from plant Temp: 88 Degrees (with fan circulating air) Humidity: 50% FFOF soil Lightly misting the top of Rating: 5