Using newspaper

It is very important to protect the water in the containers from sunlight.

With exposure to sunlight the water will develop algae and turn green and toxic to the plant roots.

I have here used newspaper to wrap the bottom of the container to prevent sunlight. This is easy to do and works nicely.

Using Cardboard

In this case for the larger container I have cut a strip of cardboard and taped it around the entire container to protect from direct sunlight.

Cardboard Protection

Here you can see the preparation of the cardboard strip before placing around the large container.

This works well because you can just lift the cardboard strip to look and check the level of liquid and the condition of the plant roots.