Tap Water in the Saltwater Reef

We will discuss why Tap water should not be used in a saltwater reef.

There has been many times that I have seen the question “Can I use tap water for my saltwater Reef“? There are many products out there that claim to make tap water safe for saltwater tanks. Are these claims true or even partly true? How are our corals or inverts affected by tap water? Are fish affected by tap water? I hope to put my experience working for a large water municipality to good use here in this article. Hopefully we can make an educated decision on tap water in the saltwater reef tank. Whether you are trying to decide to use tap water in your freshwater tank or saltwater fish only, this information might be beneficial to you also even though I don’t believe the repercussions are as severe by using tap water.

First of all let me say that not all water treatment plants are the same. They don’t use the same chemicals to treat water. They basically do have the same procedures though. There are several compounds that are used. In these compounds are heavy metals, ammonia, nitrates, phosphates, silicates, fluoride, Chlorine and various other compounds. Don’t get me wrong, these are great for us humans as far as water treatment but they are not good for our Saltwater tanks especially our saltwater reef tanks. Ammonia, nitrates and phosphates are also excessive nutrients that help to fuel algae issues in the tank. We all know what ammonia will do to fish in our saltwater tanks. Many a times folks will make their own partial water change water and are wandering where these compounds are coming from when all the time they were adding them themselves by using tap water in their partial water changes. Silicates are famous for fueling diatoms in the saltwater tank.

There are several items on the market that claim to help get rid of these compounds in our tap water. They really don’t get rid of them but just bind them so they are not as lethal as they were. They are still there. Things like the heavy metals are always there and can not be removed from the tank with these products. As I mentioned above these are good for us humans but bad for our reef tanks. In the water municipality that I work for we put out excellent drinking water but it still has these issues that our saltwater tanks have to deal with. I’ve seen many a time someone has said that there is nothing wrong with using tap water in their reef. At the beginning there is not much harm but as the tank gets older the tank accumulates more and more of these harmful compounds until finally the tank crashes and then the next thing you know someone is posting a thread asking why is my reef dead. I have seen it over and over.

How can we combat these issues in our tap water. The best thing we can do is to get something that will filter out these issues. The best bet is to get an RO/DI unit. These units can filter out 99 to 100% on these compounds. They contain pre filter units and then the water goes through a reverse osmosis membrane and then though a deionized unit. There are other types of water like RO and distilled that are not as effective as an RO/DI but still better than using tap water. My reasoning for writing this article was to help inform people about these issues in tap water.