What is Nitrate?

Saltwater aquarium nitrate develops in the third and final phase of the nitrogen cycling process.

It is what makes an aquarium’s biological filtration system function and stay in balance.

When your nitrate level builds up, it poses a problem on our saltwater aquarium.

High levels of saltwater aquarium nitrate can affect the health of the fish and corals you are keeping.

Nitrates in a reef fish tank can slow the growth of the coral reef and may affect the fish if not kept at acceptable levels.

Nitrate is also the main reason for algae blooms. It is because barine plants and algae feed on nitrate.

The ideal nitrate level in a saltwater aquarium is when it’s immeasurable.

But there are acceptable and suggested range for certain types/system of saltwater aquariums.

Suggested Levels

For reef aquariums, the suggested level is < 1.0 ppm, for FOWLR (fish only with live rock Aquarium), < 30 ppm is the suggested and acceptable level and < 0.25 ppm for Coral Reefs but not more than 5 ppm.

Nitrate can cause damage and death your anemones, corals, invertebrates and custaceans even in a minor level on a reef system.

You can also see this on our water parameter chart.

Ways to Control Nitrates

Partial Water Changes

Partial water changes over a period of time is effective but will not give you an immediate result if you want your nitrate level reduced right away.I found an article from The Spruce Pets that helped me when I struggled reducing my saltwater aquarium nitrate when it came to a dangerously high level.They found it very efficient, quickly lowering the nitrates to zero in a day. And I completely agree. This process made my saltwater aquarium nitrate low and close to zero in a day.

See image below regarding how to reduce high toxic nitrates quickly and efficiently:

Multiple Step Water Change Procedure

Graphics by Stan Hauter from The Spruce Pets

View the entire article and explanation of the image here .

It might be different on other tanks but most aquarist will say that rapid nitrate reduction is harmful to the tank inhabitants but I didn’t experienced any negative effects when I performed this process.

Do this type of water change over a longer period of time, rather than all in one day if you think that it will have harmful effects on your saltwater aquarium inhabitants.

Natural Way of Nitrate Reduction

When you use this method, the nitrifying bacteria does all the work.The three basic set ups to reduce nitrate naturally in saltwater aquarium and reef tank systems are:

  • Use live rock
  • Use live sand
  • Use a combination of both live rock and live sand

Using Denitrator Unit and Nitrate Removing Compounds & Additivesicon

  • Denitrator Unit
    Different types of denitrators work the same as the natural way of reducing nitrate. The nitrifying bacteria that grows in them does all the work.These units are very effective but they can be an expensive investment. See the image from the right as an example. Filled with Bactoballs for a huge amount of surface area, nitrate-reducing bacteria are easily maintained and fed using the enclosed Denimar tablets for precise dosing.
  • Nitrate Removing Compounds & Additives
    You can use various types of removing or absorption compounds and chemical additives to get rid of saltwater aquarium nitrate. These products are designed to absorb nitrate. Here are some nitrate absorbing products considered to be the best to help resolve high nitrate problems in saltwater aquarium and reef tank systems.

    (1) Denitrator

    Manufactured by SeaChem, De-Nitrate removes and controls nitrates, nitrites and ammonia. Also removes organic build-up and provides high porosity support for your biological filter.
    de*nitrate, 2 L / 67.6 oz.
    • Anaerobic denitrified
    • Economical to use
    • Can be used as a bio filter
    This product comes in loose form and must be contained in a mesh bag or in a filter chamber and placed in the water stream.

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    (2) Nitrate Sponge

    Nitrate Sponge is a granular zeolitic medium which works by two methods:

    1) It slowly, but directly adsorbs small amounts of ammonia that are released by fish and natural processes, and

    2) it fosters anaerobic bacterial denitrification due to its physical porous structure.

    This denitrification slowly reduces nitrate levels in the aquarium.

    Kent Marine Nitrogen Sponge for Aquariums, 7-Pound
    • Kent nitrate sponge 100gal
    • It works well in freshwater tanks or tap water to remove toxic ammonia directly
    • Nitrate sponge prolongs the time allowed between water changes by keeping nitrates low
    • Model Number: 751906000389

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    (3) Purigen

    SeaChem Purigen effectively removes protein and other organic aquarium pollutants and is a synthetic adsorbent that removes soluble and insoluble aquarium impurities.

    It controls ammonia, nitrite, and nitrate, by removing nitrogenous organic waste materials.

    On Sale
    Seachem Indoor Purigen Organic Filtration Resin - Fresh and Saltwater 100 ml
    • FILTRATION: Purigen ranges in color from almost white (cream) to light yellow. Seachem Purigen is not a mixture of ion exchangers or adsorbents, but a unique macro-porous synthetic polymer that removes soluble and insoluble impurities from water.
    • SELECTIVITY: Seachem Purigen is an organic filtration resin that works hard to remove nitrogenous compounds and waste produced by fish, corals, and even plants, making your water crystal clear.
    • CAPACITY: Being both spherical and macroreticular, Seachem Purigen has microscopic pores that increase its usable surface area to many times that of a purely spherical resin.
    • REGENERATION: Once Seachem’s Purigen is exhausted, it can be regenerated with a solution of bleach and water. The bleach will literally “burn off” the organics that have been removed from the tank.
    • SAFETY: Some slime coat products may permanently foul Purigen and render regeneration difficult. Do not reuse if odor of bleach/chlorine is detectable. In case of doubt, soak beads in small quantity of water and test for residual chlorine with a chlorine test kit.

    Purigen darkens progressively as it exhausts, and is easily renewed by treating with household bleach.

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    (4) Poly Filter Pad

    Poly filter pads quickly and efficiently remove impurities, medications, and phosphate from aquarium water.

    It also improves water clarity and actively removes harmful organic and various inorganic waste buildup for several months.

    Just cut to any size or shape to custom fit any aquarium filter and it’s ready to use.

    Poly Filter Poly-Bio-Marine for Fish Aquarium - Works for Freshwater and Saltwater Fish Tanks - Filter Aquarium Media Pads - 3-Pack of 4in x 8in Pads
    • Poly sheet is highly adsorbent chemical filter media pads quickly and efficiently remove impurities, medications and phosphate from aquarium water
    • Use in conventional power filters, under gravel filters, the chemical filtration compartment of canister filters and wet/dry filters
    • Simply cut to any size or shape to custom fit any aquarium filter
    • Rapidly improves water clarity and actively removes harmful organic and various inorganic waste buildup for several months
    • Measures 4-inch length by 8-inch width. 3 individual packages

    Poly filter changes color to indicate the pollutants being removed and when Poly Filter is exhausted.

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    (5) Nitra-Zorb

    A blend of natural and synthetic ion exchange resins that selectively remove ammonia, nitrite, and nitrate.

    API NITRA-ZORB SIZE 6 Aquarium Canister Filter Filtration Pouch 1-Count Bag, Model:110A
    • Contains one (1) API NITRA-ZORB SIZE 6 Aquarium Canister Filter Filtration Pouch 1-Count Bag
    • Removes toxins that can be harmful to fish
    • Removes ammonia, nitrite, and nitrate from aquarium water.
    • Easy-to-use pre-dosed pouch fits most canister filters on the market, for use in freshwater aquariums
    • Use when starting a new aquarium and when ammonia or nitrite is detected, replace every 2 months.

    In new aquariums,Nitra-Zorb controls the level of toxic ammonia and nitrite during initial development of the biological filter.

    In established aquariums, it helps control sudden surges in ammonia and nitrite caused by the addition of new fish, or anytime ammonia or nitrite is detected.

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These methods are just a few to consider when lowering your saltwater aquarium nitrate levels.

Just stick to your regular saltwater aquarium maintenance and nitrate levels will be at suggested levels.

If the regular cleaning and maintenance does not work, then pick one of my suggestions above.

Try different methods if one doesn’t work for you until you reach your desired level.

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