Who Gives A Fish Forums

I just set up my first 20 gallon tank and added a few Neon Tetras. The water looks cloudy after two days. Is this normal, or did I mess something up? I used Seachem Prime and have a sponge filter running.

Cloudy water is pretty common in new tanks. It's usually a bacterial bloom from the cycle starting. Give it a week, and it should clear up. Just make sure you're not overfeeding, that can make it worse.

What's your ammonia level right now? If it's above 0.5 ppm, you might wanna do a small water change. Also, how much are you feeding the Tetras? They don't need much, just a pinch once a day.

grizzlon wrote: ↑Sun Jun 29, 2025 3:10 pm Cloudy water is pretty common in new tanks. It's usually a bacterial bloom from the cycle starting. Give it a week, and it should clear up. Just make sure you're not overfeeding, that can make it worse.

Yep, exactly this. I'd also check your nitrites to make sure they're not spiking. If they are, more water changes might help.

I had the same issue with my first tank. It cleared up after about 5 days. Just keep an eye on the params and don't panic. The sponge filter is a good choice, by the way.

Did you rinse the substrate before adding it? Sometimes dust from that can cloud the water too. If it's not the bacteria bloom, that might be the culprit.

Thanks for the advice, everyone. I'll test the water tonight and cut back on feeding. I did rinse the substrate, but maybe not enough.

If you're using tap water, check if your municipality has been doing any work lately. Sometimes they add extra stuff that can mess with your tank. Happened to me once, took ages to figure out.

Cloudiness is usually harmless, but if it doesn't clear up in a week, you might wanna look into a UV sterilizer. They're pricey but work wonders for persistent blooms.

I'd just chill and wait it out. My first tank was cloudy for like a week, then it sorted itself out. Neon Tetras are pretty hardy, they'll be fine.