Who Gives A Fish Forums

My 20-gallon planted tank has been struggling for months. The plants are melting, and the fish seem stressed despite stable water params, 0 ammonia, 0 nitrite, 10 nitrate. I do weekly 30% water changes, use CO2, and have a Fluval 307. What am I missing?

First, check your CO2 levels. Too much or too little can cause melt. Also, what's your lighting schedule? If it's too intense or too long, that could stress plants. And what kind of substrate are you using? Some need root tabs to thrive.

Yeah, CO2 can be tricky. I had the same issue until I dialed it back to 1 bubble per second. Also, how old are your bulbs? If they're past 6 months, they might not be giving the right spectrum anymore.

Riveno9 wrote: ↑Sun Sep 07, 2025 5:22 pm First, check your CO2 levels. Too much or too little can cause melt. Also, what's your lighting schedule? If it's too intense or too long, that could stress plants. And what kind of substrate are you using? Some need root tabs to thrive.

I agree with this. Also, have you tested your KH and GH? Soft water can mess with plant uptake.

What plants are you growing? Some, like Anubias, don't need CO2 at all. If you're forcing high-tech plants in low-tech conditions, they'll struggle. And what's your temp? Too high can melt some species.

What plants are you growing? Some, like Anubias, don't need CO2 at all. If you're forcing high-tech plants in low-tech conditions, they'll struggle. And what's your temp? Too high can melt some species.

Thanks for the suggestions. I'll test KH and GH today. The plants are mostly Java Fern and Amazon Sword. Lighting is 8 hours a day, and the substrate is Eco-Complete.

Eco-Complete's decent, but Swords are heavy feeders. You might need root tabs. Also, Java Fern doesn't like being buried—attach it to driftwood or rocks. And yeah, check that CO2, dude. It's a fine line between lush and melt.

hillock wrote: ↑Mon Sep 08, 2025 1:39 pm What plants are you growing? Some, like Anubias, don't need CO2 at all. If you're forcing high-tech plants in low-tech conditions, they'll struggle. And what's your temp? Too high can melt some species.

Exactly. Also, how's your flow? Too much can stress plants, especially delicate ones like Java Fern.

I'd cut the light to 6 hours for a bit. Sometimes less is more, ya know? And maybe add some floating plants to shade the others while they recover. Frogbit's great for that.