How To Dose Nitrates in a Saltwater Aquarium

Some saltwater aquarists run into nitrate deficiency issues a few weeks after setting up a reef tank. This may be due to the the skimmer or roller mat being far too efficient at doing the job they were designed to do, and stripping the system of nitrates. Nitrates also have the potential to bottom out when using macroalgae such as Cheatomorpha in a refugium to control nutrients. Whatever the reason for preventing plummeting nitrate, this article will look at how to dose nitrates in a saltwater aquarium. 

Dosing Nitrates in a Saltwater Aquarium

Why dose nitrates in a saltwater tank?

If you are reading this article there is a very strong possibility you have found yourself in one of two potential scenarios, and feeding your fish extra is just not helping to get the nitrate to increase.

1. Dosing nitrate to combat dinoflagellates

Many new tank owners, and even seasoned new tank owners have like myself, have had to deal with dinoflagellates. A common consensus is that the immergence of ‘bacteria in a bottle’ in conjunction with dry ocean rock has made dinoflagellates a new menace to the saltwater hobby. In order to gain control of your nutrient levels, and rid your system of dinoflagellates, dosing often becomes a requirement.

2. Dosing nitrates to meet your corals needs

Keeping corals requires that you keep your nitrate levels stable, with at least trace amounts of both nitrate and phosphate. However, some systems tend to not be able to maintain even trace amounts of nitrate without some help. Nitrates have been found to increase populations of zooxanthellae in coral resulting in brighter, more colourful coral. It is an essential requirement that must be addressed.

Brightwell Aquatics NeoNitro Balanced Nitrogen Supplement - Reef Nutrient Enhancer for Ultra-Low Nutrient Systems - Aquarium Water Treatments, 16.9 fl oz
  • SALTWATER AQUARIUM - NeoNitro Nitrogen Supplement is a nitrogen source for nitrogen-limited, low-nutrient saltwater tanks. It works well with Microbacter7, Reef Biofuel, Katalyst, and NeoPhos to achieve the desired nutrient content in a reef aquarium
  • NATURAL PHOSPHORUS UPTAKE – NeoNitro balances carbon, nitrogen, and phosphorus for improved health and coloration of inhabitants. It balances without resorting to polluting the reef aquarium with additional organic material, for a clean ecosystem
  • MICROBIAL BIOMASS ENHANCEMENT - Facilitates removal of organic material, converting it into microbial biomass. Microbes exported from the system are captured by corals, recycling the once-latent organic material

What are the benefits of dosing nitrate in a saltwater aquarium?

  • Dosing nitrate ensures a steady controlled increase of nitrate only

    As much as your fish may relish it, increasing the amount of food you feed your fish, also increases your phosphate.  The last thing you want, if well controlled, is to increase the phosphate level in your tank as a side affect of trying to increase your nitrate.

  • Dosing nitrate can be cheap:

    Nitrate can be purchased in powder form and diluted with RO water. The dilution rate requires the smallest amount of powder which ensures that it will last for a long time.

  • Total control of nitrate levels:

    Once you have become used to dosing nitrate, your desire to keep it at any desired level is achievable.  You no longer have to hope that the food you are feeding will get you to the required level.

What do you use to dose nitrate?

Potassium nitrate (also known as Saltpetre) is easy to come by as it is commonly used for curing meat and medical purposes.  This of course means that it will be of food grade quality. Food grade is suitable to use in your aquarium without any adverse effects. Do not use Stump Remover as it is mixed with other ingredients.

Questions have been asked regarding the use of potassium nitrate against sodium nitrate.  The emphasis being the concern of a rise in potassium, should you choose to use potassium nitrate.  However, in my experience I have had no adverse affect, and the theory is that potassium in much like other minor trace elements which quickly become utilised by your corals. My choice to use potassium nitrate comes down to accessibility.  I find it far easier to obtain than sodium nitrate.

Another way of dosing nitrate is to use Brightwell Aquatics NeoNitro which comes in a ready to use liquid form.

HUMCO 263794001 Potassium Nitrate FCC 4 oz, Shape
  • Flavors for medication
  • Medical oil
  • Medical liquids

How to dose potassium nitrate in a saltwater aquarium

Potassium nitrate is easily diluted in RO water to the following mixing ratio:

RO water:  423ml
Potassium nitrate:  1/4 teaspoon

Simply measure out the required RO water into a jug and stir in the potassium nitrate until fully dissolved.  I keep my mixture in a 500ml bottle.

If your system is nitrate deficient, you may even find that you will not see an increase at all in the beginning.  If this is the case, continue to add the mixture until you do see an increase, testing after each addition.

Starting dose:  1ml for each US gallon will raise your nitrate by 1ppm

Once you’ve started seeing detectable nitrates, it’s time to take note of your tank’s consumption.  As soon as you have an idea of the amount of nitrate your aquarium consumes, you can begin to plan a dosing schedule to keep on top of your coral’s requirements.

My experience dosing nitrate

My frag tank suffers from a deficiency in nitrates.  The total volume is 35 gallons with four fish, and numerous SPS, LPS and soft coral.  I found that my corals very quickly consumed all nitrate available and no amount of extra feeding helped to increase the nitrate level. If anything, increased feeding had more affect on increased phosphate levels.

When I first began dosing, each dose seemed to do nothing. I increased the dose and eventually began seeing detectable nitrate.  In my situation, I realised that doubling the measurement of potassium nitrate in the 423ml RO water to 1/2 a teaspoon helped to keep on top of the daily nitrate depletion easier.

Dosing nitrate in a saltwater tank will be different for each system, but if you start as recommended and build up slowly, you will soon know how much to dose and how regularly.

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This is a guideline to start you off, but you will soon discover what your aquariums needs are and consequently how much nitrate you will need to dose to achieve your desired level. Once you have nitrate at your preferred level, it can be easily maintained at that level by working out your tanks consumption rate, and dosing accordingly.

How To Dose Nitrates In a Saltwater Aquarium

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