If you pull on that algae does it come off easily or is it difficult to remove? If it comes off easily it is probably a type of hair algae. If it is difficult to pull off then it is probably a turf algae. The difference? Not much, other than manual removal of turf algae is difficult. :lol: Mexican Turbo Snails and Scarlet or Blue Legged Hermit crabs are the best for filamentous algae in my experience. I prefer Scarlet hermits over Blue Legs, but more people don't want to pay the price difference.