Retailer Academy

Talking Points: Step 2 Algae & Nutrient Control™

A purple disc-shaped coral covered in short round tentacles, on rock in a reef aquarium.

Nitrate and phosphate left too high feed nuisance algae, and pushed to zero they take away what coral need for key biochemical processes. Step 2 – Algae & Nutrient Control™ in the Reef Essential® system gives the customer a target for their type of reef and a remover for each nutrient: HR Nitrate Remover™ above 15 ppm nitrate, LR Nitrate Remover™ at 15 ppm or below, and AR Phosphate Remover™ for the phosphate a test can see and the phosphate it can't. This article gives you the targets, the dose bands from the Aqua Care Guide™, the limits, and what to say at the counter.

What Step 2 – Algae & Nutrient Control™ Covers

The Guide starts Step 2 once the aquarium has cycled and the inhabitants are healthy. In the Guide's terms, algae is a photosynthetic organism that relies on light and unwanted nutrients to grow out of control.

The cost is more than looks. Algae can cover sand, rock, glass and coral — the Guide warns it can suffocate coral. It can also block the filter, and reduced flow can mean bacterial die-off, lower oxygen and a drop in pH.

Name the limits before the products:

  • Live plants: the manufacturer's pages for all three removers say not to use them in aquariums containing live plants. The Guide gives the reason — they may restrict the plants' nutrients and lead to starvation.
  • Nitrate removers need 7+ dKH and pH 8.2+: the bacteria give off carbon dioxide, which may slightly lower pH when alkalinity and pH sit below those levels.

The Step 2 shelf, as the Algae & Nutrient Control collection carries it:

  • HR Nitrate Remover™: nitrate above 15 ppm.
  • LR Nitrate Remover™: nitrate at 15 ppm or below, and ongoing maintenance.
  • AR Phosphate Remover™: ionic and chemically bound phosphate, at all ranges.
  • Bio-Active Carbon™: coral toxins, organic waste, unwanted nutrients and discoloration.
  • Sweet Coralline™: the algae a customer wants. It provides the major, minor and trace elements coralline algae need, and helps raise pH and stabilize alkalinity.

Nitrate and Phosphate Targets by Aquarium Type

Start every Step 2 conversation with the customer's targets, not a bottle. The Guide sets them by the type of reef chosen in Step 1:

  • LPS/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.

None of these is zero. The Guide calls nutrients a double-edged sword: too high and they harm the reef, bottomed out and coral lose what they need. Then it puts the job plainly.

Fortunately, the solution is simple; understand which nutrients cause algae, implement methods to control them and uphold your maintenance regime.

How to Lower Nitrate in a Reef Aquarium

Both nitrate removers work the same way: they feed bioavailable carbon to denitrifying bacteria, which convert nitrate into chemically inert nitrogen gas. The difference is range, and the hand-off sits at 15 ppm.

HR Nitrate Remover is for nitrate above 15 ppm. The Guide says it's formulated for safety and efficiency at high nitrate, to bring it down to 15 ppm. Dose daily, by the nitrate reading:

  • 15–30 ppm: 1.5–3.0 mL/day per 100 L (26 gal)
  • 30–45 ppm: 3.0–4.5 mL/day per 100 L (26 gal)
  • 45–60 ppm: 4.5–6.0 mL/day per 100 L (26 gal)
  • Above 60 ppm: 6.0 mL/day per 100 L (26 gal)

At 15 ppm, the customer switches to LR Nitrate Remover, built for precision at lower nitrate. The Guide says it can help control the red slime associated with prolonged dosing of generic carbon formulations, which makes it safe for continuous maintenance for the life of the aquarium.

  • 0.1–1.0 ppm: 0.1–0.5 mL/day per 100 L (26 gal)
  • 1.0–5.0 ppm: 0.5–1.0 mL/day per 100 L (26 gal)
  • 5.0–10.0 ppm: 1.0–2.0 mL/day per 100 L (26 gal)
  • 10.0–15.0 ppm: 2.0–3.0 mL/day per 100 L (26 gal)

The Guide's method for LR: test, dose daily until nitrate reaches the target, then note that daily dose. That becomes the maintenance dose.

Why Phosphate Tests Low When Algae Keeps Growing

Phosphate comes in two forms. Ionic phosphate in the water shows up on standard test kits; phosphate chemically bound with calcium on the live rock doesn't. Algae and bacteria can still use the bound form — the Guide says that's often why a customer reads low phosphate and still has problems.

Bound phosphate also skews calcium readings, the false-uptake trap covered in Why the Five-Step System Runs in Order. The Guide says to fix it as soon as possible.

AR Phosphate Remover removes ionic and chemically bound phosphate at all ranges, and frees up the bound calcium. The manufacturer notes that media and carbon sources take the ionic form but are slow on the bound form, because of its high chemical stability. Dose daily, by the phosphate reading:

  • 0.03–0.25 ppm: 0.1–1.0 mL/day per 100 L (26 gal)
  • 0.25–1.0 ppm: 0.5–2.5 mL/day per 100 L (26 gal)
  • 1.0–5.0 ppm: 1.0–5.0 mL/day per 100 L (26 gal)
  • 5.0–10.0 ppm: 5.0–10.0 mL/day per 100 L (26 gal)
  • Above 10 ppm: 10.0 mL/day per 100 L (26 gal)

Tell the customer the readings won't fall in a straight line. The Guide says that as phosphate drops, dosing no longer follows a linear pattern — mainly because the bound phosphate is being removed.

What to Say at the Counter

Find out their salt and their reef type first, then ask for the nitrate and phosphate readings. Match each reading to its band.

"My phosphate test says it's low, but the algae keeps coming back. Is my test wrong?"

"Not necessarily. Phosphate can bind with calcium on your rock, and a standard test can't see that form. AR Phosphate Remover takes out the free and the bound phosphate, so dose it by your reading and keep testing."

"My nitrate is at 40. Can I just use the low-range one?"

"At 40 ppm you'd start on HR Nitrate Remover — it's built for nitrate above 15 ppm. Once you test at 15, switch to LR Nitrate Remover for the long run."

"How low should my nitrate go? Zero?"

"Not zero. Coral need some nutrients. For a mixed reef, the target is 0.1–2.0 ppm nitrate and 0.03–0.09 ppm phosphate. We'll set yours by what you keep."

Q Tip Dose by real water volume. The Guide's formula is the aquarium plus the external filter, minus the volume of media, rock and ornaments.

Step 2 runs for the life of the aquarium, not just until the algae clears. Test, dose to the band, note the maintenance dose, and move on to Step 3 – Aragonite Enhancers™ once the nutrient targets hold.

Frequently Asked Questions

Do reef tank nitrate removers need a deep sand bed?

The manufacturer says HR Nitrate Remover™ and LR Nitrate Remover™ feed denitrifying bacteria in filter media, deep sand beds and the inner pores of live rock. A sand bed is one of those three places, not the only one.

Can nitrate and phosphate removers go on a dosing pump?

Yes. The manufacturer says HR Nitrate Remover™, LR Nitrate Remover™ and AR Phosphate Remover™ can all be used on a dosing pump. Sweet Coralline™ can't.

How can you tell AR Phosphate Remover™ is being overdosed?

A fine white film building on the glass. The manufacturer says that means the dose is too high and should be adjusted.

Where does the phosphate go after AR Phosphate Remover™ removes it?

The manufacturer says it precipitates both ionic and chemically bound phosphate into the filter wool or socks already in the system.

How often should Bio-Active Carbon™ be replaced in a reef tank?

Every month. The Guide says to rinse it in RODI water and place it in a high-flow area; the manufacturer also allows a reactor on its slowest setting.