5 Reliable Aquarium Water Conditioner For Your Fishtank

The first thing you learn as a newbie aquarist is that you absolutely need fish water conditioner if you want your fish to remain happy—or even alive in its tank.

That’s because the nice public officials in charge of tap water quality don’t really know (or care) whether you use the water from the tap for your pretty fish.

They only care about the water’s safety for human use and consumption.

So you can’t just add the tap water to your tank because the elements that make it good for people may make it bad for your fish. For example, some people still drink tap water, despite the prevalence of bottled water.

Water officials make sure to add chemicals to the water to make it safe to drink. They may put in chlorine or chloramine to kill the nasty bacteria that can harm people. But these chemicals may be harmful to the fish instead.

top rated aquarium water conditioner

In some places, the water pipes are somewhat older, so they contain an inordinate amount of lead. But lead doesn’t dissolve as quickly in alkaline water, so the experts put in heavy metals that can raise the pH level of the water. These traces of heavy metals may not be dangerous for us, but they’re not quite as innocuous to fish.

But you can solve these problems by using a tap water conditioner.

What Is an Aquarium Water Conditioner?

How to Use It?

Water Conditioner Reviews

So which brands are great? Here are some of our picks:


1. Seachem Prime

It’s only right we start with the Seachem Prime. After all, when it comes to aquarium water treatments, it’s a genuine bestseller. And not only did it manage to get almost 900 reviews on Amazon. What’s really astonishing is that it managed to get a high average rating with so many customer reviews.

With the 500-ml container, you can treat as much as 5,000 gallons of tap water. It removes the chlorine and the chloramine from the water, it converts ammonia into a non-toxic form, and it also detoxifies nitrite and nitrate so that the bio filter can remove them more efficiently.

It’s not acidic, so the water’s pH isn’t affected. But it does render any heavy metals in the water safe for animals and plants. And it doesn’t over-activate your protein skimmers. It even encourages fish to produce and regenerate their slime coat naturally.

This Prime is the flagship product of Seachem, and it’s a certified hit. You also get very specific directions. You just add a capful (5 ml) for every 50 gallons of water. If you’re adding less water, then just add the corresponding dosage. You can use the cap, as each thread in the cap corresponds to about 1 ml each.

Just add it to the new water, but if you’re adding it to the aquarium directly then you need to base it on the volume of the aquarium water. If the chloramine level is significantly high, use a double dosage. For emergency nitrite detoxification, use up to 5 times the normal dosage. But only use half a dose if the temperature of the water is over 86 degrees F and the chlorine and the ammonia levels are low.


  • It has received numerous rave reviews and it’s a bestseller, so you know it really works well unless all the hundreds of reviewers on Amazon are lying.
  • It encourages natural slime coat production.


  • The directions can be hard to memorize, so type the instructions in your smartphone, and don’t lose the manual.

2. API Tap Water Conditioner

Take a look at the 16-ounce container, which roughly translates to 473 ml.

It’s extremely concentrated, as a single ounce can treat up to 600 gallons. It’s also designed to remove chlorine and neutralize chloramine.

It detoxifies heavy metals, and it can be used for saltwater and freshwater tanks. It’s also safe for all aquatic life.


  • It comes with a detailed dosage guide.
  • Its concentration means that the entire 16-ounce container can treat up to 9,600 gallons, so it lasts longer (almost twice as much) than the Prime.
  • It’s safe for humans to use, which is why some people use this to add to their shampoos after swimming in a pool. It can also be used to rinse your bathing suit.


  • The dosage instructions start with 20 gallons, so small tanks require special instructions. You’ll need to buy an eyedropper, and then you’ll need to contact API to estimate how many drops you need for your small tank.
  • It doesn’t do anything for the ammonia in the water.

3. Tetra AquaSafe PLUS

This is another cheaper alternative to the Prime in terms of volume, especially for a 1-liter (33.8-ounce) container.

It is however, costly in terms of how many gallons it can actually treat. That’s because you need to use 5 ml for 10 gallons or 7 drops per gallon. So we do math, and 1 liter can treat only up to 2,000 gallons.


  • It treats everything that the Prime does, including the ammonia.
  • ​It adds vitamins and minerals for your fish in the water.
  • It even features stress-reducing slime.
  • The bottle actually functions as a dispenser. You can use the cap to measure the dosage, and you can also squeeze the bottle to put in drops.


  • It’s very expensive. It’s more than twice as expensive as the Prime.
  • The slime isn’t always a good thing for fish, especially when they don’t need extra.

4. Aqueon Tap Water Conditioner

Check out the 16-ounce container. You just need 5 ml for every 10 gallons of tap water. Just take a teaspoon (that’s 5 ml) and put it in.

It’s colorless and odorless.


  • It works very well, and does most of the same things Prime does.
  • It’s quite affordable.


  • It doesn’t encourage natural slime coat regeneration as Prime does.

5. Hagen Fluval Water Conditioner

Have a look at the price for the 16.9-ounce container, seems reasonable.

However, you’ll use this up more quickly, since you need 10 ml for 10 gallons.


  • It works well too, without any ill effects on the fish.


  • It’s much more expensive, since you’ll use it up much faster than the Prime.

Do Aquarium Plants Need Water Conditioner?

Does Fish Tank Water Conditioner Expire?

Final Recommendations

If you haven’t noticed yet, I’m quite partial to the Prime.

It’s tried and tested, and it really works. There are no side effects to worry about, and the price is just right.

Every other conditioner on the market today has to be compared to Prime, as it sets the standard for the category.


As one of our readers correctly pointed out, we did not mention the Nutrafin Aquaplus.

That was because I did not have any personal experience with that product.​

You can nonetheless give it a try, especially if you have fish that are sensitive to stress.

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