u/WildCreamPie0721

A few people on my last thread asked for tips, so here's the short version.

My method differs quite a bit from what most other users or shops recommend:

• Lots of natural light
• Indoor light/grow-light LEDs don't cut it
• Cooler water — not icy, but around 12–17°C (54–63°F) most of the time
• Never above 20°C (68°F), or bacteria inside the marimo become active
• Tap water's fine — safe for you to drink means safe for marimo
• Skip salt/fertiliser entirely — it just feeds unwanted algae
• Don't house it with other aquatic plants or animals
• Use a tank of 10L (2.5+ gal) or more — the small container it ships in heats up fast, like soaking in a hot bath

Good luck!

Bought this marimo back in 2019 from a little souvenir shop in Sapporo, Japan — it was only about 9mm–1cm then (📷1). Today, seven years on, I moved it back into its original container for old times' sake (📷2).

Happy marimo keeping, everyone! ✌️

Fewer people seem to claim "my Marimo is photosynthesising!" based on bubbles right after a water change these days 😅 - but just to clarify with Photo 2, which was taken a few days ago, about 10 days after the last water change. What you're seeing in Photo 2 is actually oxygen released by the Marimo rising to the surface.

When Marimo are actually photosynthesising, they don't get covered in lots of bubbles all at once - they release oxygen very gradually, just a tiny bit at a time.

Also, whether a Marimo floats or sinks comes down to its density rather than photosynthesis. Larger Marimo tend to float more easily because they're hollow inside. That said, even if yours stays at the bottom, photosynthesis is still happening perfectly fine under the right conditions!

Just drop a quick line - It's been very hot in London UK recently, yet my marimo are getting by. I hope yours are doing OK, too.

I think so!

As I’ve mentioned in other threads, I highly recommend buying the biggest Marimo you can find. I’ve seen so many cases where people buy nano-sized ones, expect them to grow quickly like tulips or crocuses, and then get discouraged by how incredibly slow they actually grow. In the worst-case scenarios, they just lose interest and end up neglecting them (though, to be fair, taking care of giant Marimos is no walk in the park either! 😅).

The one in the photo was about 7 cm (2.75 inches) when I bought it back in 2019, and now in 2026, it has grown to around 8 cm (3.15 inches). Compared to the tiny ones, it definitely makes a much better eye-catcher in the tank!

It's unique pressing by Blood Records - pink, red and clear splatter vinyl can be pre-ordered now. Limited to 7,500 units with hand numbered.

Assai Records (Dundee and Aberdeen) will have the TBODL instore release party on 26th May.

But personally, I think Assai Records' one looks better.