Hepper is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Seachem Denitrate Review 2023 – Pros, Cons & Verdict

Lindsey Stanton Profile Picture

By Lindsey Stanton


There are certain substances that should just not be in aquarium water, not ever. There are various substances and toxins, most of which are actually created by fish and the bacteria in the water, all of which can be poisonous to your fish. Even very small amounts of ammonia, nitrite, and nitrate can be deadly to your fish.

In fact, any ammonia and nitrite—even the smallest levels—can spell disaster for the fish in your tank. This is where Seachem Denitrate comes into play, a great solution for getting rid of all those nasty and unwanted substances in the water. This is our Seachem Denitrate review, and you definitely want to see what it is all about (you can also check the current price here).

wave divider

Ammonia, Nitrite, Nitrate & Your Aquarium

Saltwater coral reef aquarium at home is most beautiful live decoration
Image credit: Vojce, Shutterstock

Ammonia is a naturally occurring substance in nature, but so is cyanide. Our point is that ammonia is very poisonous for your fish. In all reality, the level of ammonia in the water needs to be as low as humanly possible. Even a little bit of this stuff can spell the end for your fish.

The main source of ammonia in an aquarium is fish waste, as well as uneaten and rotting food. Therefore, the more fish you have in a single tank, the faster ammonia is going to build up.

Ammonia does get turned into nitrite by the beneficial bacteria in your aquarium, which are produced by your biological filter. However, nitrite is still very poisonous to your fish. These same bacteria then break down the nitrite into nitrate, which is less harmful to your fish, but in large quantities, can still be deadly. Eventually, the bacteria will also break down the nitrate into harmless nitrogen.

Yes, things like regular water changes and a well-functioning biological filter can take care of this, but sometimes those things are just not enough to totally take care of the problem. This is where Seachem Denitrate comes into play.

It is a backup for your biological filter, which removes any remaining ammonia, nitrite, and nitrate from the water in order to make sure that your fish stay healthy and thriving. Before you start using Seachem Denitrate, you should invest in a good testing kit so you can actually measure how much of these substances are present in the water.

aquarium plant divider

Seachem Denitrate Review


Seachem Denitrate is a pretty simple and straightforward water treatment solution for getting rid of ammonia, nitrates, nitrites, and other organic substances.

There is not too much to say about the product itself, so we aren’t going to be doing a lot of sections, but what little there is to say, you should definitely know about.

What It Is & What It Does

Seachem Denitrate is a substance that removes various substances like ammonia, nitrite, and nitrate from your aquarium through anaerobic denitrification. In simplest terms, these Seachem Denitrate tablets contain beneficial bacteria and other substances which break down ammonia and nitrates into harmless nitrogen (as well as a couple of other harmless byproducts). The point here is that Seachem Denitrate is meant to take care of the substances which your biological filter has been unable to deal with.

It is a pretty complicated process with lots of science involved, so we are not going to get too deep into it here. However, what you need to know is that these Seachem Denitrate tablets release bacteria into the water, which break down ammonia into nitrite, break down that same nitrite into nitrate, and then breaks down that nitrate into harmless nitrogen and a couple of other things. It is like a multi-step process that results in clean, clear, and substance-free water.

Image Credit: Pixel-Shot, Shutterstock

Using Seachem Denitrate

To use Seachem Denitrate, simply insert it into your filter. You can place it anywhere where there is room for it, but it is best placed next to your biological filter, as it is more or less a backup for your biological filter. It is not recommended that you just place it into the water, but if you do, you need to make some kind of basket for it, one with holes so the Seachem Denitrate can be released into the water, but not big enough so your fish can mess with the tablets.

Seachem Denitrate is best put in the filter of your aquarium. Each 1-liter bottle is ideal for a 100-gallon tank. Be sure to be careful and read the instructions on the packaging before using Seachem Denitrate. Also, it is a pretty neat solution for ammonia, nitrate, and nitrites because it can be used in freshwater and saltwater tanks.

Using Seachem Denitrate could really not be any easier. It is a quick and simple solution that will help keep ammonia, nitrite, and nitrate levels as low as can possibly be.

  • Removes ammonia
  • Removes nitrates
  • Removes nitrates
  • Safe to use
  • Easy to use
  • Big bottle, lasts a long time
  • Can be used for salt and freshwater
  • Not too effective on heavily stocked tanks

divider: bubbles


We hope that this Seachem Denitrate review has been helpful and informative. Remember, folks—even a small amount of ammonia and nitrite in the water can be deadly to your fish, so be sure to have a good biological filter, do lots of water changes, and use Seachem Denitrate if necessary.

Related Articles

Further Reading

Vet Articles

Latest Vet Answers

The latest veterinarians' answers to questions from our database