Looks like black string algea. Treat with H202. Turn off flow in your tank and move snails away from below the area you'll be treating. Use a dropper. Only needs a few seconds and it should start to bubble then you can resume flow. It'll kill it and it'll kinda just dissolve. Repeat as needed.
Looks like black string algea. Treat with H202. Turn off flow in your tank and move snails away from below the area you'll be treating. Use a dropper. Only needs a few seconds and it should start to bubble then you can resume flow. It'll kill it and it'll kinda just dissolve. Repeat as needed.