Talking Points: Step 3 Aragonite Enhancers™

When calcium, alkalinity and magnesium (CAM) run low, corals can build brittle calcite instead of strong aragonite, and pH and alkalinity swing more. Step 3 – Aragonite Enhancers™ holds all three: Aragonite A™ for calcium, Aragonite B™ for alkalinity and Aragonite C™ for magnesium, dosed together by stocking level. Below are the targets by reef type, the dose bands, where Bio-Kalkwasser™ fits, the failure mode to catch and what to say at the counter.

What Step 3 – Aragonite Enhancers™ Does in a Reef Aquarium

The manufacturer's Aqua Care Guide™ names the main components with the CAM model: C for calcium, A for alkalinity, M for magnesium. Strontium and barium are the minor ones.

Corals take these elements up from the water, which lowers their concentration. When they run low, the Guide warns of greater pH fluctuations, decreased bone density and bigger parameter swings.

Aragonite and calcite are both calcium carbonate, but aragonite's ions are arranged into a harder, denser structure that's less susceptible to pH fluctuations. CAM keeps corals building the first, not the second.

• Aragonite A: ionic and complexed calcium, with balanced strontium and barium.
• Aragonite B: a full-spectrum buffer of carbonate and hydrogen carbonate that helps provide alkalinity and stabilize pH.
• Aragonite C: ionic and complexed magnesium, with sulfate and trace elements.

The three work as a team — one bottle on its own raises its own parameter and leaves the other two where they were.

Magnesium is the easiest one for a customer to skip, and the reason not to is a chain.

Alkalinity steadies pH; magnesium steadies alkalinity.

The manufacturer adds the consequence: when magnesium is low, KH fluctuations occur more often, which may stress the aquarium.

Calcium, Alkalinity and Magnesium Targets by Reef Aquarium Type

The Guide sets CAM targets by reef type:

• LPS/Soft Coral: calcium 420–440 ppm, alkalinity 10.1–10.5 dKH, magnesium 1255–1310 ppm.
• Mixed Reef: calcium 430 ppm, alkalinity 8 dKH, magnesium 1295 ppm.
• SPS: calcium 405–420 ppm, alkalinity 7.4–7.7 dKH, magnesium 1230–1280 ppm.

Across all three, the products work to 405–440 ppm calcium, 7.4–10.5 dKH alkalinity and 1230–1310 ppm magnesium. The Guide also holds strontium at 6–10 ppm with Aragonite A.

These are the same numbers the matching Step 1 – Environmental Parameters™ salt is mixed to. So a customer's salt already tells you their Step 3 targets.

How Much to Dose for Calcium, Alkalinity and Magnesium

All three share one band, 0.5–1.0 mL/day per 100 L (26 gal), set by stocking level: Lightly stocked 0.50 mL · Moderately stocked 0.75 mL · Heavily stocked 1.0 mL per day per 100 L (26 gal).

Or dose each as required to hold its own target. 1 mL per 100 L (26 gal) raises calcium by about 2 ppm (Aragonite A), alkalinity by about 0.1 dKH (Aragonite B) and magnesium by about 1 ppm (Aragonite C).

Dose into high water flow; all three are safe on a dosing pump. The Guide also recommends breaking doses down to help increase efficiency and decrease parameter swings.

Q Tip Get the real water volume before working out a dose. The manufacturer counts the aquarium plus the sump, minus the space taken by rock, media and ornaments. The free Quantum Aqua dosing app does the math from there.

Step 4 waits until these hold. If CAM isn't steady, Step 4 – Bioactive Color Elements™ won't be taken up as easily, and the protein skimmer and chemical filtration may remove it first.

When to Use Bio-Kalkwasser™ for Low pH

Bio-Kalkwasser answers a different problem: low pH. pH can drop when the lights go off, because photosynthesis stops and carbon dioxide builds up into carbonic acid.

For a low-pH reef aquarium, the Guide recommends fresh oxygenated air and making kalkwasser part of the maintenance routine. Bio-Kalkwasser supplies calcium, hydroxide and energy, and converts excess carbon dioxide into calcium carbonate. It complements A, B and C; it doesn't replace them.

It's mixed with RODI water and dripped in through a drip system or kalkwasser reactor: 1 g · 2 g · 3 g per 4 L (~1 gal) of drip solution per 100 L (26 gal), for lightly, moderately and heavily stocked aquariums. Only the clear top layer goes in; the white undissolved material stays out.

The limit to name: no more than 18 ppm of calcium from Bio-Kalkwasser per night, counted with the customer's existing calcium dosing. While using it, they monitor pH, alkalinity and calcium.

Why Calcium Keeps Dropping Even With Dosing

The failure mode: calcium that keeps falling while the customer keeps dosing. Phosphate can bind with calcium, and it may settle onto live rock. That calcium has left the water column, so the test reads low — a false uptake.

Dosing more calcium into a phosphate problem is unnecessary supplementation, and the Guide warns it can spark a cycle that creates more bound phosphate. The fix sits in Step 2 – Algae & Nutrient Control™: bring phosphate into range first. AR Phosphate Remover™ removes ionic and chemically bound phosphate and frees up bound calcium.

One more limit: the liquid Aragonite A, B and C are listed for reef aquariums only (LPS, Mixed, SPS and NPS). A fish-only aquarium with live rock isn't on their list.

What to Say at the Counter About Step 3

Read aloud, something like this:

"Your corals build their skeleton from calcium, alkalinity and magnesium. Step 3 is three bottles that keep them steady: A, B and C. You dose all three daily by how stocked your tank is, and test to keep them on target."

"Only my alkalinity is low. Do I need all three?"

"They're made to work as a set, so dose all three, either at your stocking level or as needed to hold each one's own number. Keep the magnesium up too: when it runs low, alkalinity swings more often."

"I keep dosing calcium and it keeps dropping. Should I dose more?"

"Not yet. Let's check your phosphate first: it can bind calcium out of the water, so the test reads low even while you dose. Get phosphate into range, then see where calcium sits."

"My pH drops every night. Will more Aragonite B fix it?"

"Aragonite B helps hold pH steady, so keep it at your dose. For pH that runs low or dips at night, the manufacturer recommends fresh oxygenated air and kalkwasser: Bio-Kalkwasser, dripped in alongside your A, B and C."

Send them home with the free Reef Essential® Aqua Care Guide™, which has the CAM targets by reef type. When their CAM numbers hold, Step 4 is the next conversation. For where Step 3 sits in the system, see Why the Five-Step System Runs in Order.

Frequently Asked Questions

What is the difference between aragonite and calcite in a reef tank?

Both are calcium carbonate, with identical chemistry. The difference is how the calcium and carbonate ions are arranged: aragonite is orthorhombic and calcite is trigonal. The Guide compares it to diamond and graphite, which are also chemically the same but differ in strength.

Why does a reef aquarium need magnesium?

Magnesium is found in chlorophyll, which photosynthesis needs. That's why zooxanthellae, coralline algae and phytoplankton all use it.

What is reef tank alkalinity in ppm instead of dKH?

The Guide gives the alkalinity range Aragonite B works to as 7.4–10.5 dKH, which is 132–188 ppm.

Do Aragonite A, B and C come as a powder?

Aragonite A and Aragonite B also come as bulk powders, formulated together for a 1:1 dosing ratio. Aragonite C is currently liquid only.

Can Bio-Kalkwasser be used in a fish-only tank?

Yes. The manufacturer lists Bio-Kalkwasser for FOWLR (fish only with live rock), LPS, Mixed, NPS and SPS aquariums.