Plant stem changing colour?

[skyymanz]

Hi all,

Notice that this plant the stem changing from green to dark colour. Any expert can advise why? Is it dying? not enough nutrients?

Thank you.

[skyymanz]

Any idea????

[Urban Aquaria]

If the plants are growing well, it could just be a random color variation in the stems (or could sometimes be a transition to submersed stem color), you can just trim them away if you want to maintain consistent colors.