There are a few problems that I am highlighting here.
After a few months of planting the cuboidal terrariums, the plants are still growing well but so are the algae! It is precisely because of this problem that I do not dare venture into selling any of my terrariums because I have no solution for the algal growth other than just wiping it off with a piece of absorbent paper. Just look at the tiny specks of algae which start to grow and form a layer of greenish yucky scum that obscures the view of the plants in the container.
Here, I am highlighting another problem - the use of thick glass containers. I may have planted the container nicely with plants before but the thick glass let in too little light for the plants to grow well. In addition, the view of the plants is compromised especially through the thick rimmed cover. So, one lesson learnt is to avoid glass containers that are too thick. They may look nice but are actually not as ideal as thinner glass containers with better clarity and visibility. But one has to make sure the thin glass is not extremely thin because it has to support the weight of the soil media and plants.