This is aquatic bacopa, to the right of the pink water celery. It did really well last year. I think these stems are still living? I didn't cut them back because I wanted to keep some cover in the pond for the fish to hide in. Now that the sun has been out so much and it's warming up, the spring algae is starting to grow. Should I leave this bacopa? Or cut it way back to help eliminate some of the gunk and decaying matter in the water that the algae might feed on?