co2 wont be a huge benefit running low light but it wont hurt either if you already have the setup. the reason a lot of plant people avoid sumps is the surface agitation will let the co2 gas out and be useless to plants. good blackwater plants include mosses, ferns, anubias, and crypts. most of these require very low light and will be fine in the soft blackwater. i like to attach these plants to driftwood to get them closer to the dim light and also leaves a natural look. crypts are the only ones that will need to be planted in your substrate.



