What is an aquarium water conditioner?
An aquarium water conditioner is also known as a de-chlorinator or a chlorine neutralizer. It is one of the mandatory aquarium supplies as long as you use tap water in your fish tanks. The primary purpose of the aquarium water conditioner is to remove the chlorine and chloramines from the tap water.  It will make the tap water safe for aquarium fish.

What are Chlorine and Chloramine?
Water companies use chlorine and chloramine in tap water for disinfection. While they are harmless to humans, both can be lethal to fish. Traditionally, we could make the tap water safe for aquarium use by just letting it sit in a bucket for a day or two. It is because chlorine is highly unstable with a half-life of approximately four hours. Most of the chlorine will release into the air in a day. Nowadays there is also chloramine in the tap water because it is said to be better at disinfection than chlorine. Chloramine is a much more stable compound, and it is not going anywhere until you use an aquarium water conditioner to neutralize it.

Commercialized Aquarium Water Conditioners
Once upon a time, I have used an aquarium water conditioner in the form of crystals. Nowadays, most aquarium water conditioners come in the form of liquid in a bottle. They are reasonably cheap and easy to use. You can find them in all the pet stores as long as they sell aquarium fish.

Since there are many different brands of aquarium water conditioners out there, some new fish keepers might have a hard time deciding which one to use. Sometimes it can even be confusing which product is an aquarium water conditioner.  There are so many aquarium supplies in the form of liquid in a bottle. Here is a quick guide to identify it. If an aquarium product does not mention the removal of chlorine and chloramines on the bottle, then it is not an aquarium water conditioner.

All of the aquarium water conditioners have the very same basic purpose – to neutralize chlorine and chloramines in the tap water. Some of them have secondary functions, such as the removal of heavy metal, the detoxification of ammonia and nitrite, etc. all of which can come in handy in certain situations.

The following is a list of the most popular aquarium water conditioners currently available on the market

#1 – SeaChem Prime
SeaChem Prime has a useful secondary function. It can detoxify ammonia and nitrite for up to 48 hours. During these 48 hours, the toxic ammonia is temporarily turned into harmless ammonium. It can be beneficial for new aquariums where the aquarium nitrogen cycle hasn’t been established yet. Just keep doing partial water changes with Prime every day or every other day if there are ammonia and nitrite in your aquarium. By doing so, you can minimize the damage to your fish even in an uncycled aquarium. SeaChem also claims its product can provide fish with natural slim coat and detoxify heavy metal in the water.

Dosage: Use one teaspoon of Prime for every 50 gallons of water.
(1ml treats 10 gallons of tap water)

#2 – Kordon NovAqua+
Kordon NovaAqua+ (or NovaAqua Plus) can also remove heavy metal from the water. The manufacturer claims it can help condition water by buffering tap water and adding electrolytes. The product can also provide a protective coat. It is said to be able to reduce the toxicity of nitrite by blocking the intake of nitrite by aquarium fish. Additional features include the ability to aid nitrifying bacteria in the filter by creating a slime coat in the filter media and add some beneficial organic herbs and vitamins.

Dosage: Use one teaspoon of NovaAqua+ for every 10 gallons of water(1ml treats 2 gallons of water)

#3 – Hikari Ultimate
Hikari Ultimate can remove ammonia, detoxify nitrite, and replace skin slime coat to reduce fish stress. It can also add essential electrolytes and remove heavy metal from the aquarium water.

Dosage: Use One teaspoon of Ultimate for every 10 gallons of water.
(1ml treats 2 gallons of water)

#4 – API Stress Coat+
API Stress Coat+ is another widely used aquarium water conditioner. It can remove heavy metal, detoxify ammonia and nitrite, create slime coat for fish, and add electrolytes.

Dosage: Use one teaspoon of Stress Coat for every 10 gallons of tap water.
(1ml treats 2 gallons of tap water)

#5 – Tetra Aquasafe
Tetra AquaSafe is a very basic aquarium water conditioner with the least secondary features. It can create slime coat to help heal wounds and fish, and it can protect the fish from abrasions. There is another enhanced version called AquaSafe+ (or AquaSafe Plus) with the ability to remove heavy metal from the water.

Dosage: Use one teaspoon of AquaSafe for every 10 gallons of tap water.
(1ml treats 2 gallons of tap water)

The best aquarium water conditioner for fish

It is hard to say which one is the best since all of the aquarium water conditioners can efficiently neutralize chlorine and chloramines in the tap water. There is not much difference since they all have the very similar chemical makeup. In other words, they all do the very same main job really well. Their secondary functions are not as essential. All the talks of which aquarium water conditioner work the best is no more than personal opinion and preference. Which one to buy is entirely up to you. You can’t go wrong with any of the top brands. However, amongst all the current aquarium water conditioners on the market, SeaChem Prime has the highest concentration.  Therefore, making it the most cost-effective. It is my personal favorite.

Another note: Most of these aquarium water conditioners do not even have an expiration date. Yes, I have also checked with SeaChem customer service. They have told me Prime water conditioner will never expire. It means you can buy the biggest bottle available and save some money in the long run.