With reverse osmosis (RO), even the smallest of particles can be removed from the water supply, thus keeping it clean and free of potentially hazardous microorganisms. This concept is often used in commercial and industrial applications to provide potable water, but many households also make use of this technology. Your aquarium itself might have one equipped.
Chances are, if you leave your aquarium alone for a few days without cleaning it, the water will get so polluted that the fish might end up suffocating and dying. Even if you replace it with tap water, you’ll only add minerals like nitrates, phosphates and chlorine, as well as other heavy metals, which can all be highly toxic to invertebrates.
RO machines may be effective in removing impurities, but this also means that all the essential minerals that your aquarium life needs also get sifted away. So in some cases, you’ll need to add these back into the tank—before you do though, check with your RO filter’s manufacturer on the minerals that get filtered out by the system. Some marine salt mixes that you buy for your aquarium have some of these mineral components added in.
Signs of Purity
So how do you know when the water in your aquarium is pure after running it through the RO system? For one, the pH should remain at a steady level, and the phosphate and nitrate levels are low. Also, there should be little to no algae growth.