Marine organisms react in a very sensible way to many different kinds of pollution. In this regard there is a long list of reasons: on one side they enter contact with marine water through all of their body, and many reef animals inside of them even fill the cavities with surrounding water. On the other hand, these animals have almost never been naturally exposed to these toxic compounds, therefore during their evolution’s history they never developed any mechanism for detoxifying themselves from said substances, furthermore, the majority finds itself on a lower step of the evolutionary scale, making such an operation impossible. Therefore we have to make sure that our reef aquariums get an appropriate amount of unpolluted water. Even a concentration of stranger compounds in tap water that is normally tolerated by man can already be way too elevated for invertebrates. In the past water was freed from undesirable substances through the use of implants able to completely demineralize the liquid. Today, reverse osmosis is commonly employed instead. The substantial advantage resides in the fact that, contrarily to what happens with demineralizers, the osmosis implant does not have to be regularly regenerated. In any case the rinsed water is not properly saved, since an osmosis implant produces a lot of waste too. The working process can be described, in a simplified way, as follows: water is pressed against a membrane, permeable to its molecules but not to impurities. After the membrane there is a flow of pure water, containing only a small concentration of the initial impurities. Before the membrane, however, there is an accumulation of rejected substances. To make sure that these compounds do not block the membrane, the latter has to be continuously rinsed.
This means that only a part of the incoming water can be pressed through the membrane, the remaining part has to be able to flow on the side and drag the rejected impurities away with its current. In addition, in an osmosis implant it is also possible to interrupt the flow of water through the membrane, in order to employ it all for its rinsing. Therefore, an reverse osmosis implant does not forcedly produce only pure water, one that is fitting for an aquarium, but also a waste liquid rich in impurities. This fluid can be employed for many purposes, for example to water plants in the garden or for toilet flushing. If it is simply let flowing back in the waste, it will increment the implant’s maintenance costs. It is also important to have an elevated net pressure, since the more the latter will be elevated, the more efficient the implant’s functioning will be because it will produce less waste water. But who exactly needs an inverted osmosis implant? Is it necessary for every reef aquarium? Definitely not, since it depends in part on the kind of animals that are nurtured in the aquarium, and on another side on the impurities present in tap water. If you only nurture reef fishes, of course it will not be necessary. Even robust corals like alcyonides (i.e Sarcophyton, Sinularia and others), are usually able to live decently with the employment of tap water if not elevated in concentration of nitrates, phosphates or other impurities. However, if you nurture delicate hard corals, then the matter can be critical. It is not of course possible to definitely state that at this purpose it is necessary to employ an inverted osmosis implant, but if fairly elevated gradients of pollution were to be present in tap water then several problems could arise, problems that could be solved through the use of said equipment. In any case, it is important to know that in this manner desirable substances are also pushed away, ones that normally favor the wellbeing of animals residing in the aquarium like for example calcium, magnesium, carbonates and many others. Aquariums that are operated through an inverted osmosis implant, have therefore to be sustained with indispensable trace elements (oligoelements) through the use of commercial solutions.