unknown algae help need it

[gqlmao]

Yup like the Grizz said taking out the rocks and sand and restarting might be the best way, but that may not be an option for most. Flatworms are a nightmare... If you kill them in the tank they are extremely toxic so you have to siphon them out once the treatment comes near the end, run heavy heavy carbon and keep up water changes for a day or two to remove any toxins left behind. There's really no way to get rid of them 100 percent in the first try or two, but you can keep them under control, if you keep repeating the treatments you will eventually kill all the eggs and future generations too.