There is a lot of debate over whether it is better to keep your discus tank open, or have a cover for it.
While not having your discus tank covered allows for better accessibility to your discus, better viewing and overall convenience, it is always better to have your discus tank covered for the following reasons:
It Helps Maintain the Temperature:
By having a cover for your discus tank, you will help maintain a stable temperature. If the ambient temperature is cooler than the water temperature then you can have heat loss in your tank. Likewise if the ambient temperature is hotter than the water temperature you can find the water in the discus tank suddenly heating up. This is due to he fact that if you don’t have a cover for your discus tank, you will have heat exchange taking place at the surface of the water. Since discus are so fickle about the temperature that the water has to be, it is a good idea to have a cover.
It Prevents Predators from Eating your Discus:
At first glance this might seem rather odd, but covering your discus tank prevents predators from trying to gain access and eat your discus. In this case a predator could mean a house cat. Cats as you know love fish, and a discus fish would make quite a tasty treat for them. If you do not cover your discus tank, you may find that your household cat is fishing in there when you are not around.
It Helps Keep Your Tank Cleaner:
No matter how clean you keep your home, there is always dust and other particles floating around in the air. These particles will fall into the water, and over time can put quite a strain on your discus tank filtration system. This will lead to more frequent cleanings, and the added worry of having to skim off the top of the water from time to time.
There are many options for covering your discus tank. There are standard covers with no fixtures for lights or reflectors, covers with reflectors and fixtures for lights, and of course there are covers that have fixtures for lights, but no reflectors.
The best kind of cover you can purchase for your discus fish tank, is the cover that has fixtures for two lights and also reflectors. You will want this kind of cover, because as mentioned earlier the best combination of lights to have are two fluorescent bulbs, one daylight bulb and one cool white bulb. The reflectors help reflect the light to the bottom of the tank, where your aquatic plants need it the most, and of course reflect more light upon the discus themselves, helping to show off their splendid colors.
It Prevents your Discus from Jumping out of the Tank:
Discus are rather agile fish, and if you don’t have a cover for your discus tank, you may find that some of them tend to leap out of the tank and onto the floor. This is not a desired outcome, so you will want to cover your discus tank. If you don’t want to cover your discus tank, you can always get a wire mesh to place over the top to prevent any discus from taking flight out of the tank as well.
It Prevents Evaporation:
By having a cover on your tank, you will prevent the loss of the water through evaporation. While you will not lose a significant amount of water to evaporation, over time you will eventually need to add water to the tank. Since discus are very particular in the water chemistry they need and desire, this can be bothersome as, you can spend weeks getting the chemistry right for the discus again after adding water to the discus tank.