Seachem Prime Dosage: A Complete Guide [Calculator + Chart]

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Disclaimer: This guide is for informational purpose only. We are NOT associated with Seachem Prime and we DO NOT represent them. Our goal is to just share with you the best possible resource we can, in the most helpful way.

Alright, so you just got your Seachem Prime bottle. And you are about to add it to your tank. But what’s next? What should be the Seachem Prime Dosage?

Well, the standard dosage of Seachem Prime is adding 2 drops per gallon. Yes, simple as that. If you’re preparing for a bigger water change, then consider the ratio of 1 capful of Seachem Prime for every 50 gallons of water.

Seachem Prime Dosage:Volume:
2 Drops0.1 mL
1 Capful5 mL

For those who are in a hurry, below you’ll also find a Seachem Prime Dosage calculator that we made just for you.

But to know about what Seachem Prime is, how it exactly works, and all other related topics, I highly encourage you to continue reading till the end. I have spent hours writing and researching this post and I genuinely hope that you will find it helpful. So let’s begin!

Seachem Prime Dosage Calculator:

How to use the Seachem Prime Dosage calculator tool? Just input the value of Gallons of water for which you want to use Seachem Prime and see the result! Please read the instructions under each field for more information.

What Is Seachem Prime And What Does It Do?

Seachem Prime is a type of water conditioner. It removes chlorine, and chloramine from the water. Also, it detoxifies ammonia, nitrite and nitrate.

Whenever we do any water change, we use the tap water. Now, this tap water is safe for us but not necessarily for the fish in the tank.

The tap water can contain chemicals like Chlorine which is important in making tank water disinfected by killing the bacteria.

However, for fish Chlorine is considered to be toxic at high concentrations. And even at lower concentrations, it can stress them by affecting their gills.

So that is why the water conditioners like Seachem Prime are used that assist in removing chemicals like chlorine from the water and make it safe for the fish.

Not only that, Seachem Prime converts the ammonia present in the water into a safe non-toxic form such that it can be easily removed by the biofilter of your aquarium.

It detoxifies nitrite and nitrate, and thus allows the bio filter in removing those chemicals from the water more effectively. 

It can also detoxify any heavy metal present in normal tap water even at typical high concentrations. When you use it during cycling, it will enhance the nitrate removal process from the aquarium and it won’t cause any pH drop. 

Whether you are setting up a new aquarium, or you are adding or changing water, this product will be quite helpful for you.

This product also promotes the production of natural slime coat. This product will basically cause a physiological reaction of your fish. 

As a result, your fish will produce excess mucus surrounding their whole body. This is actually a very good benefit of this product. The slime coats will also help in protecting your fish from infections.

How Much Seachem Prime Per Gallon?

As a general rule, use 0.1 mL (2 drops) of Seachem Prime per gallon. Apply this dosage when you are doing a water change or detoxifying low levels of ammonia (around 1 ppm). 

In terms of dosage directions of Seachem Prime, you can add 1 cap full (5 mL) for each 50 gallons (200 L) of new water. You can add it directly to the aquarium, but adding it to the new water is recommended.

To help you out in the best possible way, I also emailed them asking some related questions. And I really want to appreciate their prompt and helpful support which cleared all doubts. Read on to learn more.


Here’s the text version of the above Seachem Prime email conversation:

Hi, I’m really confused about the dosage of the Seachem prime for aquarium. Can you please help me out? 1. My question is how much Seachem prime can I use per gallon? 2. What is the standard dosage of Seachem prime? 3. What amount of chlorine, chloraine, nitrite and nitrate are detoxified by the standard dosage of Seachem prime. 4. If the dosage is doubled or tripled then will the action will double or triple in similar amount? means if I double the standard dosage then can I detoxify more chlorine, chloramine, ammonia or nitrite? Looking forward to hear from you soon.

Here’s the reply I got from the support:


Here’s the text version of the above Seachem Prime email conversation:

Hi there, thanks for reaching out!

The standard dose of Prime is 2 drops per gallon (1mL per 10 gallons).

The standard dose will detoxify 4mg/L Chloramine, 5mg/L Chlorine, 1ppm Ammonia and 2ppm Nitrite/Nitrate.

Yes, if you double or triple the dose, then you would double or triple the detoxification as well.

Hope this helps!

Seachem Support

Seachem Prime Dosage Chart:

Water Volume:Dosage (in mL):Dosage (in drops):
1 Gallon0.1 mL2 drops
2 Gallons0.2 mL4 drops
3 Gallons0.3 mL6 drops
5 Gallons0.5 mL10 drops
10 Gallons1 mL20 drops
20 Gallons2 mL40 drops
30 gallons3 mL60 drops
50 Gallons5 mL100 drops
75 Gallons7.5 mL150 drops
125 gallons12.5 mL250 drops
150 Gallons15 mL300 drops
180 Gallons18 mL360 drops

*This chart shows the Seachem Prime Dosage for only low levels of ammonia (about 1ppm)

For elevated ammonia levels you have to increase the dosage.

Condition:Dosage:Dose Type:
For elevated levels of ammonia (about 2 ppm), nitrite, chlorine, or chloramine0.2 mL for 1 GallonDouble Dose
Very elevated levels of ammonia (about 3 ppm) or nitrite. (Usually chlorine or chloramine concentration at this level in tap water is unheard)0.3 mL for 1 GallonTriple Dose
Extremely elevated levels of ammonia (about 4 ppm) or nitrite. (Usually chlorine or chloramine concentration at this level in tap water is unheard)0.4 mL for 1 GallonQuadruple Dose
Extremely elevated levels of ammonia (about 5 ppm) or nitrite. (Usually chlorine or chloramine concentration at this level in tap water is unheard)0.5 mL for 1 GallonMaximum Dose

Related Questions:

How Much Seachem Prime For 3 Gallons?

For 3 gallons of water, you should use 0.3 mL or 6 drops of Seachem Prime. 

How Much Seachem Prime For 5 Gallons?

For 5 gallons of water, you should use 0.5 mL or 10 drops of Seachem Prime.

How Much Seachem Prime For 10 Gallons?

For 10 gallons of water, you should use 1 mL or 20 drops of Seachem prime.

How Does Seachem Prime Work?

The working of Seachem Prime involves the formation of bonding with chlorine from the water. And then, the formation of bonding with the ammonia until it is consumed by biological filtration.

Although the bond is irreversible, ammonia is still present for your bacteria to consume. Seachem Prime will not halt the cycling process you carry for your fish tank.

Seachem Prime works on nitrites and nitrate almost in a similar fashion as it works on Ammonia. So that means it is bound and held in an inert state until the bacteria present in the biological filter are able to use it.

In other cases, they may be also reduced to nitrogen N2 gas or converted into a benign organic nitrogen compound. The end result is that

In simpler words, Seachem Prime won’t remove any of the three nitrogenous compounds mentioned. Rather, it DETOXIFIES, the ammonia, nitrites, and nitrates for up to 48 hours. So your fish will remain safe from the toxins for a short period of time.

When it comes to fish tank water, we often use tap water and then think about treating it and making it fish-safe. But what about bottled water? To learn more, read: Can You Add Bottled Water In Fish Tank?

When To Again Add The Dose of Seachem Prime?

Seachem Prime will remove chlorine and chloramine permanently. Actually, these chemicals are broken down in a form such that they won’t re-associate in water. On the other hand, the ammonia, nitrite, and nitrate detoxification will last for 48 hours in general.

So if you are using Seachem Prime mainly to detoxify ammonia or nitrite, you should re-dose it for every 48 hours. And you should do this until you feel that the bacteria colonies in your tank are large and stable enough to consume these chemicals.

As a general rule, you can dose Seachem Prime every 24-48 hours.

By the way, speaking of fish tank water, have you ever noticed that your fish tank water disappears after some days even though you filled it up to the brim? Well, that’s because of evaporation. Check out the most common reasons why fish tank water evaporates and the fixes.

Does Seachem Prime Go Bad?

Ideally, Seachem Prime doesn’t go bad if you store it properly. So it should last almost indefinitely. Seachem Prime has a very distinct odor like that of sulfur and this is totally normal.

And even if you notice a difference in scent, then don’t worry. Depending on the parameters in the warehouse when the product was manufactured, the Seachem Prime can vary in smell.

The change in smell will not affect the functioning of the product. So you can still safely use it.


Here’s the text version of the above Seachem Prime email conversation:

Hi, Can you please guide me with the following doubts: 1. Does Seachem Prime go bad? 2. Is change in smell the sign of bad smell in Seachem Prime? 3. How long a Seachem Prime bottle lasts if we open the seal, use half the bottle and store the rest of bottle with a loosely closed lid? 4. Can You give a general timeframe guide of how long can the seachem prime bottle last if we keep the bottle open? Suppose can we use a 5 years old seachem prime bottle? I really appreciate your support. Looking forward to your assistance and helpful clarification 🙂

Here’s the response I got from the support


Here’s the text version of the above Seachem Prime email conversation:


In short, to answer all of your questions, Prime never expires! 🙂

Whether it is opened, or unopened, it will last you indefinitely. The smell is normal and the strength of the smell can vary from batch to batch but does not impact the effectiveness of the product. The bottle you have could be 30 years old and still stay in solution and maintain its effectiveness as it is extremely stable. Essentially, as long as it is not boiled, or frozen solid, it should always be effective.


Seachem support

FAQ: Does Seachem Prime® expire?

Info: Seachem Prime® dosing instructions

FAQ: My Seachem Prime® smells bad or different. Is there something wrong with it?

How Long Does Seachem Prime Take To Work?

Usually, the Seachem Prime works almost instantly to remove chlorines, chloramines, and to detoxify ammonia, nitrite, or nitrates in the water.

Chemicals like chlorine are toxic and stressful for your fish. So it is important ensure that the tank water is fully neutralized before you add your fish. Now the good thing is, as soon as you will add Seachem Prime it will start working almost instantly.


Here’s the text version of the above Seachem Prime email conversation:

Hi, I was wondering a few more questions about the Seachem Prime. 1. Can I add Seachem Prime with fish in the tank? 2. Can Seachem Prime kill my fish? 3. Does seachem prime kill beneficial bacteria? Looking forward to hear from you soon.

Here’s what I got from the in response:


Here’s the text version of the above Seachem Prime email conversation:

Hello Praveen and thanks for reaching out!

I will answer your questions in the order they were asked for sake of clarity:

  1. Yes, when used as directed, Prime can be added directly to a tank containing fish.
  2. When used as directed, Prime should not cause harm to any of the tank inhabitants. However, if grossly overdosed, it can reduce the oxygen in the water, causing the fish to suffocate.
  3. Prime does not cause any harm to beneficial bacteria and will NOT lock up ammonia, nitrite or nitrate where the bacteria can’t access it. The bacteria can still utilize all of those compounds in the presence of Prime.

I hope this helps!

Seachem Support

Final Words

So that’s it about the Seachem Prime Dosage. I hope all your doubts are clarified by reading this post. If you have found any value, I highly appreciate it if you can share this post with others.

Thank You! And by the way, I’m also on YouTube. So feel free to check out my videos there. You can find my channel with the same name “eFishkeeping.”

By the way, speaking of fish tank water, have you ever noticed your fish coming to the top of the tank right after you do the water change? Then I highly recommend reading this guide where I explain the exact reasons for that phenomenon.

Also Read: How Long To Wait To Put Fish In Tank After Conditioner?