|MadSci Network: Botany|
Hi, I think the problem is not only on light, also on other organisms in water. Some kinds of microorganisms such as green algae will grow in presence of light, and they grow very fast. In this process, they use oxigen and nitrogen in water, thus compete with your plants. As to the plant itself, to my current knowledge, the root will not be inhibited by light. So I think you should change the plant in to untransparent container, and change the solution after a period of time. Good luck.
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