Is It Okay to Add Water Conditioner with Fish in the Aquarium?

Chlorine and chloramine are added to tap water for the purpose of killing harmful bacteria. These chemicals are very efficient disinfectants that can be safely consumed by humans and terrestrial animals in small doses. However, they’re toxic for freshwater and saltwater aquarium fish, and this is why water conditioners are used to treat tap water before it’s added to a tank. All water conditioners are formulated to eliminate chlorine and chloramine, but you can also find special conditioners with added ingredients such as vitamins, colloids, herbal extracts, and electrolytes.

All ingredients in water conditioners are safe for freshwater and saltwater fish, invertebrates, plants, and nitrifying bacteria. You can certainly add water conditioner to your aquarium when fish are in the tank because it’s safe. However, there are a few additional things to consider.

Understanding Water Conditioners

The most simple formulation of water conditioners consists of diluted sodium thiosulfate, which can only neutralize chlorine. If you live in a region where water is disinfected with chloramine, which is the most widely used in the U.S., you’ll need a water conditioner with sulfonates. Fish keepers who get reverse osmosis water from their aquarium supplier or who have a special filter installed in their aquarium don’t need to use water conditioners. However, they’ll need to supplement for the lack of electrolytes in the form of Replenish from SeaChem, RO Right from Kent, or others.

Neutralizing Heavy Metals in Tap Water

All water sources contain some levels of heavy metals. In the case of drinking water, those metals include mercury, fluoride, dioxin, and lead. Freshwater fish swim in natural habitats that don’t contain these heavy metals, which is why some water conditioners are formulated to eliminate this potential toxicity.

Using Water Conditioners the Right Way

For the best results, always follow the directions on the label of the conditioner bottle, which will include the proper ratio. Conditioners formulated with vitamins, herbal extracts, and electrolytes may require a higher ratio. Without exception, you should never pour untreated tap water in the aquarium. When you’re doing partial water changes, the first step is to measure how much water you’ll take out. For example, for a 20-gallon tank, the recommended 25-30 percent water change every two weeks will require you to gather and treat 5-8 gallons of water. We recommend Prime from SeaChem because it neutralizes immediately. Depending on the conditioner, it may take between 15 minutes to an hour for the treatment to be completed.

Adding Water Conditioners with Nutrients

The only time you should to add water conditioner directly in the tank is when it has herbal extracts, vitamins, electrolytes, and medications. Follow the instructions on the label to learn about the right amount to use and the correct frequency. The main purpose of water conditioners is to treat H2O before it’s introduced in aquatic habitats.

It’s also important to treat your water with the proper conditioner if you have a pond. For all of your aquarium and pond equipment needs, reach out to Aquatic Warehouse. We offer a wide array of essential supplies on our website, or you can stop by our store in Kearny Mesa to get what you need. If you have any questions for our friendly and knowledgeable staff, please feel free to give us a call at 858-467-9297.