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I've got a 20 gallon tank with a bunch of guppies and just added some java moss. It's been a week and the moss looks a bit brown. Water params are good, 0 ammonia, 0 nitrite, 10 nitrate. Lighting is moderate, 6 hours a day. Any tips to keep it green?

Java moss can turn brown if it's not getting enough light or if there's too much organic waste. Try increasing the light to 8 hours and see if that helps. Also, make sure you're not overfeeding the guppies.

daxler wrote: ↑Fri Sep 19, 2025 5:12 am Java moss can turn brown if it's not getting enough light or if there's too much organic waste. Try increasing the light to 8 hours and see if that helps. Also, make sure you're not overfeeding the guppies.

Yep, that's spot on. I've had the same issue before. Adding a bit of liquid fertilizer might help too, but go easy on it.

My java moss thrives with guppies, but it took a minute to dial it in. I run my lights for 7 hours, use a sponge filter, and do weekly 20% water changes. The moss loves the flow from the filter, so maybe check your current setup.

What kind of substrate are you using? I've heard java moss does better with a nutrient-rich base, but I'm still new to this.

trigade wrote: ↑Mon Sep 22, 2025 10:34 am What kind of substrate are you using? I've heard java moss does better with a nutrient-rich base, but I'm still new to this.

Java moss doesn't really need substrate since it's usually attached to rocks or driftwood. Just make sure it's not buried.

I've found that java moss does best with consistent water changes and stable params. Guppies are chill tankmates, but they can nibble on the moss if they're hungry. Maybe try feeding them a bit more often.

I've found that java moss does best with consistent water changes and stable params. Guppies are chill tankmates, but they can nibble on the moss if they're hungry. Maybe try feeding them a bit more often.

Thanks for all the advice, everyone. I'll try increasing the light and adjusting the feeding routine. Appreciate the help!