Foundation ABC 3x250ml — Calcium, Alkalinity and Magnesium Trio - Red Sea

The Foundation ABC 3x250ml pack from Red Sea brings the three foundation elements of the Reef Care Program together in one box: calcium, alkalinity and magnesium. Three 250ml bottles, one per element.

Red Sea explains the Foundation program in its own words:

And for a longer walk-through of the whole Reef Care Program — major elements, trace elements, algae management and coral nutrition — this independent explainer covers the ground well:

Why the three belong together

This is the point Red Sea repeats on every page of its documentation: the foundation elements complement each other, and if one runs short it immediately becomes the limiting factor for all growth. Dosing calcium into a tank with low magnesium does not raise calcium; it makes both precipitate.

A coral builds roughly 90% of its skeleton by combining calcium and carbonate into aragonite. The rest comes from magnesite, strontianite and minor minerals. When magnesium or strontium run low, the skeleton forms with more calcite — more brittle. That is why the trio is sold as a set.

What is in the pack

• Foundation A — Calcium+: calcium, strontium and barium. 1ml raises calcium in 100L (25 gal) by 2ppm.
• Foundation B — KH/Alkalinity: carbonate and other seawater buffers. 1ml raises alkalinity in 100L by 0.036 meq/l (0.1 dKH).
• Foundation C — Magnesium: magnesium salts. 1ml raises magnesium in 100L by 1ppm.

Size: 3 x 250ml · Suitable for: reef aquariums with SPS, LPS and soft corals, manual dosing or dosing pump.

Target levels for your reef tank

Pick the row for the most demanding species in your saltwater tank. Marine fish tanks are tested weekly; reef tanks are dosed daily.

How to dose: the manufacturer's method

The concentrations above convert a measured gap into millilitres. They are not doses. Red Sea describes a method for finding your daily dose:

1. Bring all three elements to their target values.
2. Run 4 days without dosing anything, topping up evaporation with fresh water.
3. Test. Work out each element's dose to return to target: that is the "4 day dosage". Add it.
4. Divide by 4: that is the daily dose for the coming week.
5. Retest weekly. If the gap changes noticeably, adjust the daily dose.

If an element ends up above its target, wait for the excess to be used up before resuming daily dosing.

Three rules not to skip

• Daily maximums: calcium 20ppm, alkalinity 0.5 meq/l (1.4 dKH), magnesium 10ppm. Larger gaps get spread over several days.
• Dosing order: magnesium first, alkalinity second, calcium last — 10 minutes between each. That is what prevents precipitation.
• Where to add it: into the sump. Without a sump, slowly into a high-flow area, away from direct contact with fish and corals.

Goes well with

When one bottle empties faster than the others — often the magnesium, dosed in larger volumes — replace it individually in 500ml: Foundation A Calcium+, Foundation B KH/Alkalinity or Foundation C Magnesium.

Once the base is stable, the next step of the Reef Care Program is trace elements: Trace Colors ABCD supplies the 31 minor and trace elements tied to stony coral pigments.

Frequently asked questions

Is the 3x250ml trio cheaper than three separate bottles?

Yes, for a total volume of 750ml. It is the format built for starting the program or running a modest-sized tank; the individual 500ml bottles take over once consumption is established and you know which one goes fastest.

Can all three be dosed at the same time?

No. Red Sea specifies an order — magnesium, alkalinity, calcium — with 10 minutes between each addition. Adding them together causes precipitation.

How often should I test?

Weekly, even once the daily dose is dialled in. Uptake shifts as corals grow and as the tank's population changes.

Do I need a test kit?

Yes. Red Sea's entire method rests on measurement: without calcium, alkalinity and magnesium tests there is no way to calculate the daily dose.

Why buy from ReefSolution

Aquarium ReefSolution is an authorized Red Sea dealer. Our team works in marine aquariums in Laval and knows the Reef Care Program from real tanks, not just from the label. We ship across Canada and offer in-store pickup.