Nutrient Deficiency (Yellowing Leaves)

Yellowing leaves usually mean your plants are running low on nitrogen or iron — common in tanks without regular fertilizing. A liquid plant fertilizer replaces what the water column alone doesn't provide.

Why this happens

• Low nitrogen or iron in the water column, common in tanks that aren't regularly fertilized.
• Fast-growing or heavily-planted tanks use up available nutrients faster than a lightly-stocked tank replenishes them.
• Old, established leaves naturally yellow and drop as a plant redirects nutrients to new growth — not always a deficiency.

What to do next

1. Add a liquid plant fertilizer on a regular schedule (check the product for dosing frequency).
2. Trim off badly yellowed leaves so the plant can focus energy on new growth.
3. Check whether it's isolated to older leaves (often normal) versus new growth (more likely a genuine deficiency).
4. Consider root tabs for heavy root-feeders like swords or crypts, since liquid fertilizer alone may not reach the substrate.

Frequently asked questions