Even though a Marimo Moss Ball is algae, its not the type of algae that will spread throughout the aquarium. The algae in a Marimo Moss Ball will not turn tank water green. Moss Balls can often be sold on the small side, around 2 inches in diameter.

Do Marimo Balls cause algae?

Marimo moss balls suck up the same nutrients as undesirable algae, depriving invasive algae of those nutrients. I had brown algae growing in my 10-gallon tank, but since wiping them off the glass and adding a few moss balls, they have yet to grow back.

Do moss balls turn water green?

If your marimo turn brown, make sure they're moved to a cooler location with less direct light. They may recover and turn green again on their own.