Buyer’s Guide: Best Aquarium Water Conditioner Reviewed in 2019

Water conditioner is a staple in my aquarium kits. The easiest way to ensure your water is aquarium safe.

But they’re not all the same quality when it comes to how much you’ll get for your money.

Sneak peak – the pricier options may be cheaper than you think when you look deeper.

In this guide, I’ll provide you with everything you need to know about aquarium water conditioners, so you can then use my product reviews the for the best water conditioner so you can buy the best one for you.

Seachem Prime is my number one pick.

What is Tap Water Conditioner?

Tap water conditioner is a blend of chemicals used to make tap water safe to put into an aquarium.

Some conditioners can also be used in an emergency to detoxify compounds in the water while you figure out and adjust the root cause.

Why You Need Water Conditioner

The biggest reason to use water conditioner is to make water from a municipal water supplier safe to put into your aquarium.

To prevent water borne illnesses, municipal water (city, county, water company water, etc.) is treated with chemicals that kill bacteria and viruses.

The two most common chemicals used to disinfect water are chlorine (Cl) and chloramine (NH2Cl).

These two additives are great for drinking water, because they kill germs and don’t affect humans, but they’re bad news for fish, aquatic reptiles, amphibians and invertebrates that come into contact with them.

Basically, chlorine and chloramine go straight into the bloodstreams of these kinds of animals and poisons them. When aquatic animals are exposed to chlorine/chloramine, it’s like they get bleached inside and out.

And yes, that’s just as terrible as it sounds.

Some water conditioners also detoxify things like ammonia, nitrite and nitrate. So they’re good to have on hand in case of emergencies where your water parameters temporarily get out of whack.

Pro Tip: Water conditioners are no substitute for proper tank maintenance. Make sure you’re changing out 25%-50% of your water each week and vacuuming your substrate.

What’s the Difference Between Chlorine and Chloramine?

In the past, municipal water supplies used regular chlorine to disinfect drinking water. But there are some problems with this.

Pure chlorine is pretty unstable. At room temperature, it’s a gas, so it can easily dissipate from the water it’s dissolved in.

If drinking water is exposed to the open air, all of the chlorine will evaporate out of the water completely over the course of a day.

This can be a bad thing and mean that by the time water travels from the treatment plant, to its final destination, all of the chlorine has dissipated.

That means it can again carry water borne bacteria and viruses.

But chloramine is different.

It’s made by binding ammonia to chlorine. It’s much more stable and doesn’t just evaporate into the air the way chlorine does.

More water suppliers are switching to chloramine since it lasts longer than chlorine.

This is great for preventing water borne illness, but not so great for aquarists.

You can’t just leave water out in a bucket and wait for the chloramines to dissipate like you can with chlorine.

If your water supply uses chloramine, you absolutely have to use water conditioner or it will kill your fish and invertebrates.

How to Tell if There is Chloramine in Your Tap Water

There are two main ways you can do this:

Ask Your Water Supplier

Call your water company and ask them what they use to disinfect the water.

You can also try checking their website. I did a web search asking what kind of disinfectant my local water supplier used and was able to find the information within minutes.

Test Strips

If you want to check for yourself, another good way to tell if there’s chloramine in your water is to use a test strip that measures both free and total chlorine.

Free chlorine measures chlorine that isn’t bound to anything. So it would show you regular chlorine, but chloramine wouldn’t register on this part of the test strip.

Total chlorine shows you the levels of bound and unbound chlorine. So both regular chlorine and chloramine would show up on this part of the strip.

If both numbers are about the same, your water supply uses regular chlorine.

If total chlorine is much higher than free chlorine, your water supply is using chloramine.

That means using dechlorinator is an absolute must for you.

Are There Times You Don’t Need Water Conditioner?

Yes, technically, there are times when you can get away with skipping water conditioner.

Well Water

If your water comes from your own private well, instead of a municipal water supply, then no chlorine or chloramine has been added to it.

Letting Water Sit Out

In the olden times, of the 1980s, (which technically was 30 years ago, and last century, dear Lord I’m old) most aquarists let their water sit out for 24-48 hours and the chlorine would dissipate on its own.

These days, you can do this IF your water company uses chlorine and not chloramine.

This does not do anything for nitrite, nitrates or heavy metals.

For me, this is impractical. I change out an average of about 80 gallons every week. I just don’t have the room to let that much water hang out for days.

Pro Tip: Sitting out does not remove chloramine. You need a water conditioner to eliminate chloramine.

Boiling the Water

Boiling water for 20 minutes will remove chlorine from your tap water.

But again, it will not remove chloramine.

For me, this is even more impractical. No way do I have the patience to boil 80 gallons of water, plus wait for it to cool down.

That would take all day. Honestly, I love my fish, but not that much!

How to Choose Your Water Conditioner

There are a few things you want to consider before you buy your water conditioner.

Price Per Gallon

Let’s face it, price can have a lot to do with which water conditioner you decide to purchase.

I’d love to have an unlimited aquarium budget, but unless I win the lottery, I’ve got to get the best bang for my buck.

I really urge you to take a look at how many gallons a bottle of conditioner treats when you’re figuring out which one is the best value.

Pro Tip: The label should tell you how many gallons the whole bottle treats. If you divide the price by the number of gallons the bottle treats, that will give you the price per gallon.

So one bottle might cost a few dollars more, but it treats 5 times as much water as the cheaper bottle. It’s good to compare and figure out the price to use the product, not just to purchase it.

Price of the bottle ÷ number of gallons bottle treats = price per gallon

Compare the price per gallon and you might find that “bargain” brands really aren’t a great value because they don’t treat as many gallons per bottle.

Chloramine Removal

Chloramine is a compound of both chlorine and ammonia. Some conditioners remove just the chlorine and leave behind the ammonia. This can really stress fish since ammonia is so toxic.

If your tap water contains chloramines, it is best to use a conditioner that removes chlorine and detoxifies ammonia.

Best Aquarium Water Conditioners Reviewed

Now you have a better understanding on what water conditioner does and how to choose your own, you can use the following review to make an informed buying decision.

1. Seachem Prime (Top Pick)

Gallons treated – 500 milliliters treats 5,000 gallons (18,927 liters)
Cost per gallon – approx. $0.002 ← not a typo, less than a penny per gallon ($0.0006 per liter)
What does it remove/do to water?
– Ammonia
– Nitrite
– Nitrate
– Heavy metals

OK, I have to admit some bias when it comes to this product. This is what I’ve used in all of my tanks for years. Not only is it a good water conditioner to use for ordinary water changes, but it’s also a good thing to have on hand in case of emergencies.

You can use Prime if you have a sudden spike in ammonia, nitrite or nitrate. It will detoxify these compounds and keep your fish out of the danger zones while you deal with the root cause of the problem.

It does not contain ingredients to build up a fish’s slime coat, something some other conditioners offer.

One thing that people do complain about is that Prime smells strongly of sulfur.

And yes, it does sometimes smell like sulfur.

But frankly, I have never found this to be a big deal. As soon as I pour it into the tank, the smell goes away.

And I always err on the side of adding too much rather than too little.

I have never noticed that it makes my tanks smell funny in the slightest. Don’t get me wrong, I’m not going to be dabbing it on for perfume, but the smell really isn’t a thing.

Great value, one fifth of a penny per gallon
Removes chloramine and protects fish from ammonia
Good to have on hand in case of emergency

Does not include anything for slime coat
Smells like sulfur

2. API Tap Water Conditioner

Gallons treated
Chlorine only – 473 milliliters treats 9,460 gallons (35,810 liters)
Chloramine – 473 milliliters treats 2,838 gallons (10,743 liters)
Cost per gallon –
Chlorine only –  approx. $0.0007 per gallon ($0.0002 per liter)
Chloramine – approx. $0.002 per gallon ($0.002 per liter)
What does it remove/do to water?
Detoxifies heavy metals

API Tap Water Conditioner does a great job of clearing chlorine out of your water. It’s also effective at detoxifying heavy metals.

But, it does not contain anything that detoxifies ammonia. So, if you have chloramine, it will eliminate the chlorine and leave the ammonia it was bound to. This could mean elevated ammonia in your tank that adds to fish stress.

Since this conditioner does nothing to deal with increased ammonia levels, I’d pass on this one if you have chloramine in your water. On top of that, it takes more of this conditioner to treat chloraminated water, so the price per gallon is no better than Prime.

Removes chlorine
Detoxifies heavy metals
Great value per gallon

Does not detoxify ammonia, not the best choice for chloramine
Does not include anything for slime coat

3. Aqualife Complete Water Conditioner

Gallons treated – 473 milliliters treats 960 gallons (3,630 liters)
Cost per gallon – approx. $0.02 per gallon ($0.005 per liter)
What does it remove/do to water?
Stimulates slime coat production
Increases alkalinity (KH)
– Ammonia
– Nitrite
– Nitrate
– Heavy metals

Aqualife Complete is comparable to Seachem Prime when it comes to what it eliminates and detoxifies.

One aspect of this conditioner can be either a pro, or a con, depending on your tap water. It increases the alkalinity (carbonate hardness) of water.

Pro Tip: Carbonate hardness (KH) refers to the amount of carbonate and bicarbonate dissolved in water. The more KH is in your water, the higher your pH will be because the carbonate/bicarbonate will neutralize any acids in the water

If you have soft water, or struggle to keep your tank’s pH from crashing, adding some more KH is a great thing. You’d basically be getting two treatments for the price of one.

Aqualife Complete also stimulates slime coat production.

All fish are covered in a thin layer of mucus over their scales, gills and fins. That’s why fish are so slippery and feel kind of gross and slimy.

Products like Aqualife Complete contain ingredients that stimulate a fish’s body to produce extra slime. This is thought to help fish recover from stress, illness and injuries more quickly.

But if you already have hard water, with a high pH, you probably don’t want additional KH in your water. So you might want to pass on this one.

Another point about Aqualife Complete: it’s not the best value. A 473 milliliter bottle only treats 960 gallons. And since a bottle that size costs so much more than an equivalent bottle of Prime, the price per gallon is 10 times as much.

Eliminates chlorine/chloramine and protects fish from ammonia spikes
Good to have on hand if there is a sudden spike in ammonia, nitrite or nitrate

Not as good a value, costs 10 times more per gallon than Seachem Prime
Some aquarists may not want the added alkalinity

4. Aqueon Water Conditioner

Gallons treated – 473 milliliters treats 946 gallons (3,580 liters)
Cost per gallon – approx. $0.007 per gallon ($0.002 per liter)
What does it remove/do to water?
– Ammonia
– Nitrite
– Nitrate
– Heavy metals
– Stimulates slime coat

Aqueon Water Conditioner, like Prime and Aqualife Complete, eliminates and detoxifies a wide range of harmful substances.

It doesn’t make other changes to water parameters, like adding alkalinity, so you don’t have to worry about it increasing your pH.

This conditioner also has the added benefit of stimulating slime coat.

My big thing about Aqueon Water Conditioner is that it is more than 3 times more expensive than Prime. I just don’t think that’s a great value.

Eliminates and detoxifies a broad range of substances
Stimulates slime coat

Cheaper price for the bottle, but price per gallon is more than 3 times higher per gallon than Prime


5. Aquatic Experts TankFirst Premium Complete Water Conditioner

Gallons treated
Regular formula – 500 milliliters treats 1,000 gallons (3,785.41 liters)
Concentrated formula – 500 milliliters treats 5,000 gallons (18,927 liters)
Cost per gallon –
Regular formula – approx. $0.01 per gallon ($0.003 per liter)
Concentrated formula – approx. $0.003 per gallon ($0.0008 per liter)
What does it remove/do to water?
– Ammonia
– Nitrite
– Nitrate
– Heavy metals

TankFirst is a water conditioner that removes and detoxifies in much the same way that Prime, Aqualife Complete and Aqueon do.

But, TankFirst’s claim to fame is that it does not use ingredients that have a strong smell. They advertise that fish have a great sense of smell (some in fact do), and so, pouring strong smelling chemicals into the tank can stress them out.

Here’s my thing about this: I’ve seen no evidence that this is the case. Fish don’t freak out and swim away when I add Prime. I’ve never seen any change in their behavior from adding it.

Also, the company doesn’t seem to have anything like scientific studies to back up their claims. And there aren’t a bunch of user experiences shared online that go along with this either.

This might be good for the few people who claim that Prime makes their aquariums smell bad.

But since this has never been my experience, I would once again base my choice on price. TankFirst is slightly more expensive than Prime. So I’m afraid Prime would again have to win out…again.

Doesn’t have a strong smell like Seachem Prime
Concentrated formula is a good value per gallon, almost as good as Prime
Removes and detoxifies a wide range of compounds
Doesn’t promote slime coat
No proof the smell of other dechlorinators bothers fish
Not quite as good a value as Prime

Which Water Conditioner is Best?

After reading this article, take a wild guess which one I decided I prefer.

Yep, Seachem Prime.

And no, Seachem is not paying me a bunch of money to promote their products.

Although, if they did want to cut me a big fat check, I wouldn’t be upset about that either.

I promised myself that I would keep an open mind while I was writing this article. I knew that I preferred Prime, but everyone should always be open to new information, myself included.

But I have to admit, after running the numbers on all of these different products, I came right back to the conclusion that Prime is the best water conditioner.

I don’t really buy the claim from Aquatic Experts that the smell of Prime bothers aquarium fish. I’ve added Prime to my tanks literally hundreds of times at this point.

The fish don’t try to escape from the new water or even swim away when I dose Prime directly into the tank.

So it all comes down to this: I want a water conditioner that gets rid of chlorine/chloramine, and detoxifies nitrite and nitrate and has a decent price. Prime is the clear winner.

Water Conditioner FAQs

Lets run through some common FAQs

When to add water conditioner?

In my opinion, you should add water conditioner to any water that you add to the tank. Whether you’re doing a big water change, or just topping off for evaporation, use water conditioner.

Don’t risk exposing your fish to chlorinated/chloraminated water.

How much water conditioner to use?

Carefully read the instructions on the bottle of water conditioner.

I like to use medicine droppers or those little cups for measuring liquid medications for kids. They make measuring out water conditioner easier.

How often to use water conditioner in the aquarium?

Under normal circumstances, you really only need to add water conditioner when you are adding tap water to your aquarium.

The only other time to add it is when you test your water and find that you have a spike in something like ammonia, nitrite or nitrate.

If that happens, start out with a 50% water change and then dose the tank with a water conditioner that detoxifies ammonia, nitrate and nitrite.

Make sure to use enough to treat the entire volume of water in the tank.

Final Words on Aquarium Water Conditioner

I hope you’ve gleaned from this article that water conditioner is pretty darn important. More than likely, the water out of your tap needs to be treated, or it could kill your fish.

It’s important to take a look at the price per gallon to figure out the real value of a product. It’s not about the price to buy the product, what’s important is the cost to use it.

After giving all of these brands a fair shot, I still think that Seachem Prime came out the winner. It has the best value as far as price per gallon for a conditioner that dechlorinates and detoxifies other pollutants.

Katherine Morgan

Hey, there! I'm Katherine from Northwest Florida. I've kept aquariums for over two decades, enjoy experimenting with low-tech planted setups and an avid South American cichlid enthusiast.
Katherine Morgan

Last update on 2019-10-22 / Affiliate links / Images from Amazon Product Advertising API

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