If you're adding water to your system, you must make sure it's free chlorine and chloramines so that you do not destroy your biofilter.
Nearly all companies manufacture a product that removes chlorine. None of those, however, can compare in quality, concentration, or effectiveness to Seachem’s flagship product: Prime®. Prime® is the second most concentrated dechlorinator on the market after our own aquavitro alpha™. A single 100 mL bottle will treat 1000 US gallons of tap water. Prime® will remove both chlorine and chloramines from municipal water supplies.
Prime® also contains a binder which renders ammonia, nitrite, and nitrate non-toxic. It is very important to understand how those two functions work together. All dechlorinators operate through a chemical process known as reduction. In this process, toxic dissolved chlorine gas (Cl2) is converted into non-toxic chloride ions (Cl-). The reduction process also breaks the bonds between chlorine and nitrogen atoms in the chloramine molecule (NH2Cl), freeing the chlorine atoms and replacing them with hydrogen (H) to create ammonia (NH3).
Typically, dechlorinators stop there, leaving the water full of ammonia! Seachem takes the necessary next step by including an ammonia binder to detoxify the ammonia produced in the reduction process.
Be very careful when purchasing water conditioners. If your municipality includes chloramines in the water supplies, a standard sodium thiosulfate dechlorinator is not enough. Prime® promotes the natural production and restoration of the slime coat rather than relying on artificial or non-native slime compounds. A further bonus for the reef hobbyist—Prime® will not overactivate protein skimmers.