Marimo moss balls are cute velvety balls that have become a favorite, low-maintenance pet plant for some people. Kind of like when pet rocks were a thing. Despite their name, they are actually made of algae, not moss.
If you’re planning to purchase one or are currently taking care of one, here are the top tips to keep your Marimo moss balls flourishing in your care:
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Table of contents
- 1. Provide Marimo Moss Balls with Medium to Low Exposure to Indirect Sunlight
- 2. Use Treated Tap Water for your Marimo Moss Balls
- 3. Ensure the Marimo Moss Balls Are Placed in an Open System Vessel
- 4. Keep the Water & Surrounding Temperature Cold at 17-23°C
- 5. Don’t Put Marimo Moss Balls with Fish & Invertebrates that will Damage Them
- 6. Wash your Marimo Moss Balls Once Every Other A Week in Another Container with Clean Water
- 7. Move your Marimo Moss Balls in their Vessel Every Other Day by Stirring the Water Gently
- 8. Squeeze your Marimo Moss Balls when They Float to Release Air from Within
1. Provide Marimo Moss Balls with Medium to Low Exposure to Indirect Sunlight
These moss balls originate from somewhere deep in the ocean, where sunlight is very minimal. Kind of like dust bunnies under your bed. You need to emulate the same light environment for them so they’ll thrive. With that said, don’t attempt to give them direct sunlight. The resulting consequence is they will turn white, stunting their growth. Kind of like that nasty sunburn you once got that one time you didn’t wear sunscreen – it’s an unpleasant experience, youch. Don’t do your moss balls dirty like that.
Occasional sunlight is fine because, as forms of algae, they still need light to photosynthesize. But it’s better to keep the light as low as you can and indirect. An ideal place would be in a bright room where the windows are covered by a curtain. If your home doesn’t have a window, you can use LED grow lights (Amazon link) to supplement the moss ball’s light needs.
2. Use Treated Tap Water for your Marimo Moss Balls
One of the main reasons naturally grown Marimo moss balls in open water are declining in population is the excessive levels of nutrients in the water, aka eutrophication. While this is unlikely to happen in a home setting, it’s better to err on the side of caution. So the best type of water you should house your moss balls in is one with relatively low to no nutrients, such as distilled or filtered water. Moss balls don’t even need much fertilizing or nutrients to grow as is. They are algae – they’ll grow regardless of such things when all the right factors are present.
If your tap water is not ‘hard water, it’s fine to use regular tap water. Because it means there is no heavy concentration of mineral salts in the water. If that’s not the case, you can treat your tap water with a water treatment solution (Amazon link).
3. Ensure the Marimo Moss Balls Are Placed in an Open System Vessel
Some articles go around saying you can house moss balls in a closed jar; some even managed to keep them in terrariums. I can’t imagine how but the maintenance must be a strict regime to keep them thriving. Like all plants, Marimo moss balls need fresh air to grow well. Once all the available air in a closed-system vessel is gone, there’s nowhere else the moss balls can get their air supply from.
So don’t coop it up in a closed container just because it’ll look good. The moss balls will end up turning brown because of this. So keep your Marimo moss balls in an open-system vessel like in an aquarium, a fishbowl, or even a glass of water.
4. Keep the Water & Surrounding Temperature Cold at 17-23°C
Marimo moss balls flourish in cold waters – the colder it is, the better. This may be a problem if you live in warmer climates. Come summertime, when it’s hot enough to feel like you want to take your skin off, your Marimo moss balls won’t survive.
You’ll probably need to keep the air-conditioning blasting and ensure the cold air is focused on the Marimo moss balls in their container. A fan is not going to cut it, unfortunately. Where possible, avoid letting your Marimo moss balls taste the heat of 25°C lest you want them to turn brown and suffer from the undying heat.
You can even place your moss pet in the fridge, having it enjoy the constant cool. I mean, it’s no different to your pets trying to stay in there when the weather is too hot haha. The difference is they won’t eat any of your leftovers. Also, try to avoid plopping ice water inside the Marimo moss balls container. Instead, put the container in a large bowl with ice water, which should do the trick.
5. Don’t Put Marimo Moss Balls with Fish & Invertebrates that will Damage Them
Since Marimo moss balls are essentially algae balls, some fish and invertebrates will take a bite out of these little green balls for food. If not for food, to play rough with that could end up damaging them. Here are a few creatures you should avoid grouping with your moss balls:
- Ghost shrimp
Beta fish are your best bet if you really want to add your Marimo moss balls with other underwater creatures. They won’t eat them but will occasionally play and rest on the balls, leaving no damages at all. You can also put them in with other fish or invertebrates, provided they are a non-aggressive species.
6. Wash your Marimo Moss Balls Once Every Other A Week in Another Container with Clean Water
This is similar to dusting your houseplants with a damp cloth or brush. Think of it as a pick-me-up for your Marimo moss balls. Plus, this keeps them vibrant green and peppy, especially if they’re starting to look a little dull or brown.
If the moss balls are in the tank with other fish and invertebrates, you may have to clean them more often. Simply because they’re likely to have more dirt from being around their cohabitants.
Here is how you should clean your Marimo moss balls:
- Take them out of their vessel.
- Place them in a container with clean water. Again, make sure it is treated water and not regular tap water.
- Hold them gently in your hands and swish lightly in the water a few times. Give it a light squeeze to squish out any dirty water, kind of like a sponge. Keep doing this until it turns vibrant green again.
- Roll them in your hands to keep their spherical shape compact and set them aside in a cool area.
- Clean their vessel thoroughly and fill it with fresh, treated water before putting your moss balls back in.
7. Move your Marimo Moss Balls in their Vessel Every Other Day by Stirring the Water Gently
Wild Marimo moss balls get rolled around in open water by the currents. This is how they maintain their spherical shape, keeping them intact. But moss balls in your home tend to just sit in their vessel unless you’ve housed them with other live creatures that roll them around. If they’re in a jar on their own, it’s advisable to give them a gentle swirl in the glass or container.
You can also take them out and roll them in your hands gently or against a flat surface as well. This way, they stay firm and keep their shape. Additionally, nudging the moss balls with a bit of movement will allow even lighting on all angles. The bottom part of the moss balls most likely wasn’t exposed to any light, so even a gentle swirl is good enough to move them around.
8. Squeeze your Marimo Moss Balls when They Float to Release Air from Within
Don’t be alarmed when your Marimo moss balls float. This just means there is accumulated air stuck inside from all their photosynthesizing. In other words, they’re gassy, and they need to fart it out of their systems. Giving them a gentle squeeze usually does the trick. Kind of reminds you of burping a baby if you think about it.
This phenomenon isn’t necessarily a bad thing. In some ways, it’s one of the good signs that signify your Marimo moss balls are doing really well in your care! And even if you don’t “burp” them, eventually, they will let the air out on their own and float back down.
Important note for purchasing Marimo Moss Balls: It’s been discovered that earlier this year, in March 2021 that zebra mussels were found in Marimo moss balls. These are highly invasive invertebrates that can potentially clog up waterways when the water Marimo moss balls are housed in is infected and disposed of in storm drains.
For more information on that, here is a helpful article from the US Wildlife Care for your perusal:
Invasive Zebra Mussels Found in Moss Balls (fws.gov)
Lastly, here’s a little troubleshooting for you in case any problem arises with your Marimo moss balls:
This means it’s probably dirty and needs cleaning. Depending on how long it has gone without being cleaned, you may need to swirl it in salty water and pick out the brown parts.
However, if only one side of the moss ball is brown, this means it’s not getting enough light on that side. Turn it over so it’ll receive even lighting on all sides.
It’s likely to be filthy from accumulated dirt in its container. Give it a thorough washing, and it’ll be as good as new.
There are two reasons why this happened:
1. A lethal algae parasite is growing on it.
2. Improper care.
Whichever cause it is, your moss ball needs to be immediately cleaned and removed of all the black parts. You’ll end up with a smaller moss ball than you started with, but it is vital to trim off all the dead parts off. Monitor it for the next few days and give it the best care you can to let it recover.
There are 4 things you need to do to ensure you have genuine Marimo moss balls:
Feel the texture. It shouldn’t be smooth all throughout despite its velvet look. There should be a bumpy hardness and softness all throughout. Where possible, try to push a finger in to make sure the texture is the same all the way within. Some fakes tend to have ping pong balls in the center, so this is the best way to check.
Squish the moss ball. They should be easily molded and spongey when you handle them gently. If you find that it can’t even change shape, then it’s probably fake.
Pick it apart. I advise you to do this with permission from the store owner, even if it’s just a tiny pinch. It should come away fairly quickly, considering how fragile it is.
One thing I urge you to do when doing all your inspections is to ask the store owner first. If they refuse you to handle them, chances are you’re better off purchasing your Marimo moss balls elsewhere. It’s only by holding them yourself will you know their authenticity.
Your moss balls have been receiving too much sunlight, direct or indirect. The best thing to do is quickly put them in a dark environment so they will recover.
No. Slimy or slippery moss balls indicate there is some other kind of algae growing around them. You need to give them a thorough rinsing every day until the texture is back to normal. Additionally, place your moss balls in salty water to quicken the process and pick out any visible algae from them.
They can live over 100 years, given the right conditions and proper care to grow throughout the decade. It makes them a family heirloom in that sense.
And that’s all you need to know to keep your Marimo moss balls in tip-top shape for years to come! 😀
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