My leaves are turning yellow?Updated 2 months ago

Newly added plants may turn yellow and deteriorate due to adaptation stress. Plants shed their old leaves and channel their energy towards growing new ones - Look out for the newest leaves, if they are healthy, you are on the right track. The old leaves have limited plasticity to adapt to new environments and the plant will abandon them to focus on growing new leaves. 

Slow growers such as Bucephalandra, Anubias, Cryptocoryne species and even Java Fern often take months to show the benefits of improved nutrition. This is because of their naturally slow rates of growth.

For a tank without CO2 injection, new leaves may take several weeks (even months) to form, as the rate of growth is very slow in such conditions.

To read about how plants adapt to an improving environment, head here.

In this picture we transferred a Variegated Rotala macrandra from the shop's tank to ours. In the shop, under lower light and inadequate fertilization, the leaves are greener and the internodes are longer. After being planted into our farm tank, the new leaves produced are fully red, reflecting the higher light and fertilization levels. Notice however, that the old leaves that were grown in the shop did not produce this adaptation. They are programmed to best utilize what was available in the shop tank's environment, not the new tank, and even an improvement in their new environment cannot change that fully. This is primary because there is a significant difference in environment between the shop's tank and our own tank. 

After the plant from the picture has grown in our farm tank for sometime, we cut off the top portion that has been grown adapted to the tank and replant it, discarding the bottom portion (that was grown in the shop). The fully adapted plant preserves its older leaves longer, and even the old growth is more algae resistant as well. Notice that even the older leaves further down the stem are well colored, in good form as they are adapted to this tank.