Why are my plants turning yellow?

[mintix]

I've got a 20 gallon tank in a room that gets plenty of natural light, plus I've got a light on top of the tank. My plants have always thrived, but lately I've noticed some yellowing leaves on my Java Ferns. I'm not sure what's going on. I'm thinking of removing the affected plants, but I'm not sure if that's the right move. Should I give them a chance to recover or just take them out? What else can I do to help my plants out?

[keye30]

I think the issue might be a nutrient deficiency - I had a similar problem a while back but adding root tabs made a huge difference, my plants are thriving now.

[dungeon]

Do you supplement with liquid fertilizer as well, or just the root tabs?

[boomer]

Yellowing leaves can be a sign of several issues, not just one thing. To better understand what's going on, we'd need more info on your lighting setup and any fertilizers you're using. A photo of the tank with the affected plants would also be helpful.

[mintix]

Do you supplement with liquid fertilizer as well, or just the root tabs?

Still waiting on them to arrive, ordered some.

[shakinStevens]

Nitrogen and iron deficiencies often cause yellowing leaves in plants. If a plant is nitrogen deficient, all the leaves will turn yellow. On the other hand, an iron deficient plant will have green veins with yellow leaves. There are other possible deficiencies that can cause yellow leaves, but they're harder to identify and often result in holes in the leaves.

To test for nitrogen deficiency, check your water for ammonia, nitrite, and nitrate. If all readings are zero, you likely just need to add nitrogen to the water. You can use Seachem's nitrogen supplement or potassium nitrate. Add just enough to get a detectable amount of nitrate - 3 to 5 ppm should be sufficient.

If it looks like an iron deficiency, you'll need a fertilizer that includes micro nutrients.

[boomer]

I'd advise against rushing into nitrogen supplementation here. Java Ferns are slow growers, which means they don't require intense lighting or heavy nutrient dosing. Assuming there are fish in this tank, they'll provide more than enough ammonia/ammonium to keep the Java Ferns happy.

High-tech planted tanks might experience nitrogen deficiencies, but low-tech natuflake method tanks with fish present aren't likely to run into this issue. The ammonia from fish respiration and substrate decomposition will provide all the nitrogen the plants need.