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Reef Tank Nitrate Removal - How to Lower Reef Tank Nitrates

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Last updated on November 17th, 2023


Reef Tank Nitrate Removal - How to Lower Reef Tank Nitrates

Reef Tank Nitrate Removal

There is a lot of information available about high nitrates in saltwater aquariums. However, much of the advice includes adding more chemicals to the water, which simply isn't ideal. If you are adding chemicals for reef tank nitrate removal, you will likely end up searching for how to remove whatever else that chemical added in the process.

Instead of looking to add a pile of chemicals and hope for the best, I will encourage looking at slower, but much safer solutions to reef tank nitrate removal. This may include a few methods, such as bacteria growth, macroalgae growth, or even adding less of the source.

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Identify the Source of Reef Tank Nitrate

Before focussing on Reef Tank Nitrate Reduction, you need to focus on why your Nitrates are high to begin with. You wouldn't go into surgery without first knowing what hurts, and you likely wouldn't get a bandage without first knowing what is bleeding (and why). So why is it any different with your reef tank? Before treating high nitrates in saltwater aquariums, you need to know what is causing the high nitrates so that you can stop adding more.

Nitrates come from uneaten food, or waste that was not handled. The first thing you need to do is determine if you are feeding too much. If you feed the fish 3 times a day, there is a high chance you are feeding too much. Additionally, one of the biggest offenders is feeding corals. If you are feeding coral, a large amount of the food is not eaten. This extra food rots and increases the already high reef tank nitrates.

Feeding Coral - Reduce or Stop

In terms of feeding coral, if you have high reef tank nitrates, and all of your coral are photosynthetic, stop feeding your coral. Believe me, it will be okay. In fact, you may find that your coral grow faster due to better water conditions. If you have some non-photosynthetic coral, try cutting the amount of coral food you add in half and see if that affects the high reef tank nitrate levels, and the coral.

Feeding Fish - Reduce Stay the Same

If your fish are fat and happy, or they don't eat all of the food in the tank within a couple minutes, you may be able to reduce feeding a little. Make small changes to how much you feed because you don't want to starve the fish. Since all fish eat different food, and different amounts, I don't have great guidelines about how much to reduce. If your fish are happy and eating all of the food, you may not want to change this at all. You could also add some hermit crabs or snails to eat the excess food. Then you won't need to make any changes.

How to Prevent Reef Tank Nitrates

The first way to reduce reef tank nitrates is not to get elevated nitrate levels in the first place. Since reef tank nitrates come from decaying food and waste, you can prevent nitrates by removing the food and waste before it rots. One way to do this is to catch the food and waste when it flows down the overflow (if you have a sump). This can be done with Filter Socks or Automatic Filter Roller Mat. Both of these will catch waste before it rots. Though the filter socks require you to change them every 3 days or so to prevent waste from rotting in the sock.

To get the most out of your Filter Sock or Filter Roller Mat, Read About Micro Bubble Scrubbing.

After the waste breaks down further or gets past the filter socks, a Protein Skimmer can be used to remove smaller particles. Removing particles by blasting a chamber of water with micro bubbles and then collecting the waste, known as skimmate, in a collection cup.

Recommended Products for Preventing Nitrates

How to Reduce High Saltwater Aquarium Nitrates

If you don't run a protein skimmer, or filter media, or even that you already have nitrates, there are still a couple of solutions. One of these solutions is to carbon dose. Carbon dosing feeds bacteria allowing it to multiply more quickly. This bacteria then eats the nitrates. A few things to consider with carbon dosing includes what else is in the carbon (usually vodka), as well as how much you need to add. Finally, I have found that after some period of time, some coral like zoas do not like carbon addition. I lost a lot of very nice zoas when carbon dosing, mostly because I didn't know that I should watch them.

For more info about Carbon Dosing in the Reef Tank, read this article.

The best way to handle reef tank nitrate removal though, is using a refugium to grow macroalgae. Macro algae such as Cheato grows quickly, and pulls in nitrates and phosphates to grow. The only thing you need to ensure is that there is a strong enough light to grow the macro algae fast enough to remove nitrate from the saltwater aquarium.

Personally speaking, I find that we over-think this. There are a number of refugium lights on the market, an most of them are far more expensive than they need to be, and under-perform. Why do I say we over-think this? Because there is a group of people that are known for growing plants quickly, which is what we are doing by growing macro-algae. What group is this? Horticulturists, but more specifically I'm thinking of a group that grows plants in their homes quickly. Cannabis growers have this corner of the market figured out, at a low cost.

So what refugium do I use? I use the CANAGROW Grow Lights from Amazon. Most of the reef keepers I know that are able to grow 2 - 5 gallons or more of cheato per month are also using the CanaGrow light. Low cost, simple, and effective. This light helped me reduce my Nitrates in 300 gallons of water from 50+ ppm down to undetectable over 30 - 60 days. The best part is that the refugium maintains this for me and I don't have to do any additional work.

For more information about Reef Tank Refugiums, check out this article.

Recommended Product for Reducing Reef Tank Nitrates

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Bringing it all together, if you are trying to lower nitrates in your reef tank, you first need to know why there are nitrates. Then, you should try to prevent adding more nitrates. You wouldn't mop the floor before fixing a broken pipe, right? Once you have that in place with filter socks/roller and/or a protein skimmer, then you can treat the nitrates in your tank with carbon dosing, or even better, macroalgae in a refugium!

For more about Reef Tank Nitrate, check out My Book, Reef Tank Nitrogen, available for download (pdf) in the Reef Stable Store, or paperback/kindle from Amazon.

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About the Author

Reef Stable Founder John Krenzer

John is a Software Engineer with a passion for saltwater aquariums, as well as the founder and president of Reef Stable. He started in the aquarium hobby as a child with a 20 gallon freshwater aquarium. His interest in aquarium life grew and in 2008, John set up his first saltwater aquarium.

Today, John maintains an over 300 gallon reef tank system, consisting of a 120g reef and a 210g reef. These large tanks are contained within the same system, sharing a sump as a means to reduce total maintenance and increase total water volume.

John writes articles for the blog as a means to learn about more reef aquarium topics. These articles act as a reference for the readers as well as himself. John updates these articles frequently to provide additional information or make corrections as new information becomes available.

If you would like to request an article, tank tour article, or to collaborate, let me know via the Contact Me Page!

About Reef Stable

Reef Stable was initially founded in 2019 as a reef tank parameter log to fill a need. Reef Stable quickly grew, becoming a location to solve all of your reef tank problems as well as a place to learn.

Reef Stable now provides a Reef Blog, Reef Aquarium Guides, Coral Care Guides, Identification and Solutions for Pests and Algae, and Reef Dosing Calculators, in addition to the original Reef Parameter Log.

Reef Stable continues to grow, striving to provide a single location for all your reef tank needs!

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