Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Good stuff.

I originally bought this to control black beard algae on my plants. It did a great job with that, the algae turned red and then the otos ate it. I still use it because it is a good product but be careful because a high dose of this carbon is bad for certain plants. Read up on the various planted tank websites to make sure this won't kill your plants. With the right plants ( I have amazon Swords and Apogenatons) it is a good thing.