EcoBio-Block Stone Natural Volcanic Water Clarifier and Odor Remover Rock for Aquariums, Nano, 2-Pack

A bit pricey but these really work so worth it if you want something natural and low maintenance to help keep your tank clear and clean.

This product is and works Amazing! Works just like it says, clearer water, no more brown algae (could get rid of it no matter what we tried), and this product did its job! I thank God that lead me to it! Our Bettafish Fiji (shares a 10 gallon tank with Plackey the Pleco, and Blackie the snail), all seem to be more happier (more lively and full of energy), alert and our Betta likes being near them! Placed two of these (small ones) in our 10 gallon tank! Don’t believe the bad reviews! It DID NOT hurt our Betta Fish, Pleco or Snail at all! …And as you can See, it Cleared our tank water quick!! I Highly Recommend them!! Will be buying them Again!

Ok first off, I read the instructions and then I totally didn't follow them because I'm stupid lol. That said, I'm so glad nothing happened to my fish lol. I've only been using this for 3 days now and it seems to be harmless for the fish. Especially since I didn't wash the cubes before hand. I just through them in the tank. I know, my bad. Anyway, the water seems to be clearing up. I scrubbed the glass before putting the in but hopefully this will help keep algae from growing again.Update!It's been weeks now and the algae has gotten worse. These did absolutely nothing to help. I ended up getting some liquid from the pet store to help control the issue and it has worked perfectly. Huge difference within one day. I highly recommend getting something from the pet store not these stones

I don’t have proof of this, obviously can’t ask the fish. But as soon as I put these in not more than a week later one of my fish was dead and the other severely ill. They had been fine for months, was just trying to cut down on the green algae in the tank.After placing these in the tank my beta had damage to his tail and it took weeks of rehabbing and over $100 to replenish the bacteria, heal the fish and stabilize the plant life to fix the tank.

warning, this product damage the fins of your betta fish