Marimo Moss Balls & Water Garden Care Guide

Easy to Care for, Low Light Requirements, Simple


Japanese legend says a chief’s daughter fell in love with a commoner, and her family opposed the union. The two lovers broke free of tradition and ran away together, only to fall into a lake where together, they sank to the bottom. Their love was so strong that they were turned into Moss Balls. Their love is still said to exist in each moss ball today. AND that is why moss balls are considered tokens of love, affection and good luck


  • Moss Balls are actually a form of spherical algae
  • Marimo translates to seaweed ball…so it is kind of redundant to call Moss Balls, Marimo Moss Balls (just saying)
  • Moss Balls do not have an anchor in the center, its just solid algae that radiated from the center
  • Growth Rate: 5mm per year 
  • Moss Balls enjoy low indirect light and cool water


Keep your moss ball where they will receive low to medium indirect light. Direct sunlight can turn your moss balls brown and further degrade them by warming the water they live in. ***Moss Balls are well adapted to low light spaces and can photosynthesize in normal household light. If your space has no window, keep moss ball close to a fluorescent or full-spectrum bulb.

Changing the Water

Change water once every one-two weeks using regular tap water (for best results, allow water to sit out for 24 hours prior to changing the water). You’ll need to change the water more often in summer, as it will heat and evaporate more quickly. ***Clean your moss ball enclosure with a brush if algae begins to grow on tank surface.

Browning + Other Problems

-If your moss ball turns white or losses its vibrant green color, make sure they’re moved to a cooler location with less direct light. They can recover, turning green again. If not, you may add a tiny amount of aquarium ocean salt. If your moss ball turns brown, it is likely dirty and needs a good cleaning under running water. If you moss ball is black and falling apart, it is likely decaying from the inside out. You can try to cut out the contaminated parts, followed up by rerolling of the moss ball and crossed fingers!

Floating Moss Balls?

If you just cleaned your moss balls, there could be little air bubbles trapped in them. Give them a light squeeze in the water to try to get some of the air bubbles out, otherwise, they will settle to the bottom of their enclosure within 1-2 days

Keeping Moss Balls Round

In rivers and lakes, moss balls are jostled around by currents, helping them retain a perfectly round shape. Should you want to retain a lovely round shape, slightly agitate your enclosure once a day. The goal is to have them resting on a side different than the one they were resting on the day before.

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