Step 2 Explained: Algae & Nutrient Control™ for Reef Tanks

Introduction

It's easy to assume the cleanest reef tank is the one that tests zero for nitrate and phosphate.

The manufacturer's Reef Essential® Aqua Care Guide™ says otherwise.

Corals need these nutrients for key biochemical processes. Let them run too high, though, and they feed algae and harm your reef.

That's why the Guide's nutrient targets start above zero for every type of reef.

Step 2 – Algae & Nutrient Control™ is the part of the Reef Essential system built around that balance. In this article, we break down why algae grows, the nitrate and phosphate levels to aim for, how each Step 2 product works, and how to run the step in your tank.

What Is Step 2 – Algae & Nutrient Control™?

Step 2 is where the Guide explains what algae is, why it grows, the key molecules it needs, and how to control it.

It comes after Step 1, where you choose your salt and parameters, and after cycling, which How to Cycle Your Aquarium Quickly and Efficiently covers.

Right after cycling, a tank may go through what the Guide calls the "ugly stage," when nuisance algae can spread while the system settles. The Guide calls this normal, and a good time to build habits.

In the US, Step 2 has five products:

• Bio-Active Carbon™: removes coral toxins, organic waste, unwanted nutrients and discoloration.
• HR Nitrate Remover™: lowers nitrate above 15 ppm.
• LR Nitrate Remover™: lowers and maintains nitrate at 15 ppm or below.
• AR Phosphate Remover™: removes phosphate at all ranges, including the bound form.
• Sweet Coralline™: supplies the elements coralline algae needs to grow.

All five are on the Step 2 collection page.

Why Algae Grows in a Reef Tank

Algae is photosynthetic. It relies on light and unwanted nutrients to grow out of control.

Those nutrients start as waste. The animals in your tank produce waste that contains nitrogen and phosphorus, and bacteria and oxygen break it down into ammonia, ammonium, nitrite, nitrate and phosphate.

An algae bloom can do real harm. The Guide lists what can follow:

• Algae can cover sand, rock, glass and corals, and may smother corals to death.
• It can block your filter, adding maintenance.
• Less flow to the filter can mean bacterial die-off, a build-up of toxic molecules, less oxygen and lower pH.

The Guide's answer has three parts. Understand which nutrients cause algae, put nutrient export methods in place to control them, and keep up your maintenance.

Recommended Nitrate and Phosphate Levels for a Reef Tank

The Guide calls nutrients a double-edged sword: you don't want them bottomed out or high.

The goal is not zero nutrients.

The goal is the right range for the corals you keep.

That's nutrient balance, and the Guide sets these targets by reef type:

• LPS and soft coral: nitrate 2.0–5.0 ppm, phosphate 0.03–0.09 ppm.
• Mixed reef: nitrate 0.1–2.0 ppm, phosphate 0.03–0.09 ppm.
• SPS: nitrate 0.1–1.0 ppm, phosphate 0.03–0.09 ppm.

Phosphate stays the same for every reef type. Nitrate runs higher in an LPS or soft coral tank than in an SPS tank.

Test, then compare your results to the line for your reef. It tells you whether to bring a nutrient down or hold it.

How Nitrate Removers Work

Nitrate is one of the key molecules algae needs to grow. Removing it takes anaerobic bacteria, which live where oxygen is low.

Fed bioavailable carbon, these bacteria convert nitrate into chemically inert nitrogen gas, which leaves the water. Both Quantum nitrate removers supply that carbon. The manufacturer says the bacteria live in filter media, deep sand beds and the inner pores of live rock.

Denitrification produces carbon dioxide, which forms carbonic acid in water and may slightly lower pH. As a rule of thumb, the Guide recommends an alkalinity of 7 dKH or more and a pH of 8.2 or more while you remove nitrate this way.

HR Nitrate Remover™: Above 15 ppm

HR Nitrate Remover brings high nitrate down to 15 ppm. Test, dose daily for your reading, then switch to LR Nitrate Remover at 15 ppm.

The Guide's daily dose runs from 1.5–3.0 mL/day per 100 L (26 gal) at 15–30 ppm to 6.0 mL/day per 100 L (26 gal) at 60 ppm and above.

LR Nitrate Remover™: 15 ppm and Below

LR Nitrate Remover is built for precision at lower readings. The Guide says it can help control the red slime often linked to long-term dosing of generic carbon formulas, making it safe for the life of your tank.

Its daily dose runs from 0.1–0.5 mL/day per 100 L (26 gal) at 0.1–1.0 ppm to 2.0–3.0 mL/day per 100 L (26 gal) at 10.0–15.0 ppm.

Dose daily until nitrate reaches your target, then note that daily dose. It becomes your maintenance dose.

How to Remove Bound Phosphate

Phosphate exists in two forms, which makes it harder to read.

Ionic phosphate is dissolved in the water, and standard tests can measure it. Bound phosphate has combined with calcium and can settle onto your live rock. It isn't in the water, so a test can't see it.

The Guide notes that algae and bacteria can use both calcium and phosphate, which is often why reef keepers read low phosphate and still have problems.

Bound phosphate also pulls calcium out of the water, which can stress corals, so the Guide recommends dealing with it quickly.

AR Phosphate Remover targets both forms and frees up the bound calcium. The manufacturer says it precipitates the phosphate out of the water and into your filter wool or socks.

The Guide's daily dose runs from 0.1–1.0 mL/day per 100 L (26 gal) at 0.03–0.25 ppm to 10.0 mL/day per 100 L (26 gal) at 10.0 ppm and above. Find your maintenance dose the same way as with nitrate.

Q Tip As phosphate levels decrease, dosing no longer follows a linear pattern, mainly because the chemically bound phosphate is being removed.

The manufacturer says a fine white film building on your glass means you're overdosing it.

How to Run Step 2 in Your Tank

Here's how to put Step 2 to work:

• Test first. Every remover is dosed from your current nitrate or phosphate reading.
• Dose for your real water volume. The Guide's formula is your tank and external filter, minus the space taken up by rock, media and ornaments.
• Run a protein skimmer. We recommend one alongside the removers. The Guide calls it an efficient way to filter out excess proteins.

Clear Organic Waste With Carbon

Waste can also tint your water yellow, which may distort the light your corals need. Bio-Active Carbon removes that discoloration.

Rinse it in RODI water, place it in its media bag in a high-flow area, and replace it every month. The Guide's monthly amount per 100 L (26 gal) is 15 g or 30 mL in a lightly stocked tank, 25 g or 50 mL moderately stocked, and 50 g or 100 mL heavily stocked.

Grow the Algae You Want

Not all algae is a problem. Coralline algae adds color, and the Guide says it strengthens live rock, promotes microbial diversity and improves dissolved oxygen.

Sweet Coralline supplies the major, minor and trace elements coralline algae needs, and helps raise pH and stabilize alkalinity. The Guide's dose is 1 mL/week per 100 L (26 gal), or as needed to encourage growth. The manufacturer adds one limit: don't raise pH by more than 0.2 in a day.

Keep It Running

Step 2 isn't a one-time cleanup. Like every step except cycling, it runs for the life of your tank. For the feeding side, read Clean Nutrition, Zero Excess.

Once your nutrients are under control, the Guide moves on to calcium, alkalinity and magnesium in Step 3. The full Aqua Care Guide is free, and the Quantum Aqua dosing app works out your doses by tank size.

Frequently Asked Questions

Can Step 2 Products Go on a Dosing Pump?

HR Nitrate Remover™, LR Nitrate Remover™ and AR Phosphate Remover™ can, according to the manufacturer's product pages. Sweet Coralline™ can't, and its bottle should be shaken well before dosing.

Where Does Phosphate in a Reef Tank Come From?

From waste, which contains nitrogen and phosphorus, and from food. The Guide notes that phosphate may be present in fish foods as a preservative, and suggests straining fish food with RODI water before feeding. Straining can wash out some of the food's beneficial ingredients too.

Can I Use Nitrate and Phosphate Removers in a Tank With Live Plants?

The Guide says to take extra care, because the removers may restrict the plants' nutrients and starve them. The manufacturer's product pages go further and say not to use them in aquariums with live plants.

Do Nitrate Removers Need a Deep Sand Bed?

Not necessarily. The manufacturer says the bacteria these removers feed live in filter media and the inner pores of live rock, as well as in deep sand beds.