Foundation A Calcium+ 1L — Calcium, Strontium and Barium for Corals - Red Sea

Foundation A Calcium+ from Red Sea supplies calcium, strontium and barium in the ratios found in stony coral skeleton. 1 litre liquid bottle — the middle size, for an established reef tank whose consumption you already know.

Why strontium and barium matter

A coral builds roughly 90% of its skeleton by combining calcium and carbonate into aragonite. The rest comes from magnesite, strontianite, calcite and other minor minerals.

When magnesium or strontium run low, the skeleton forms with a higher proportion of calcite — a more brittle structure, easier to damage. Adding calcium alone does not correct that. It is why this is a blend rather than a plain calcium solution.

Specifications

• Elements: calcium, strontium and barium
• Concentration: 1ml raises calcium in 100 litres (25 gal) by 2ppm
• Daily maximum: 20ppm of calcium per day
• Sizes: 250ml, 500ml, 1L (this listing), 5L and 1kg powder
• Suitable for: SPS, LPS and soft coral reef tanks · dosing pump compatible

Target levels for your reef tank

How to dose: the manufacturer's method

The "1ml = 2ppm" figure converts a measured gap into millilitres — it is not a dose. Red Sea's method for finding your daily dose:

1. Bring Ca, Alk and Mg to their target values.
2. Run 4 days without dosing anything, topping up evaporation with fresh water.
3. Test, work out the dose to return to target, add it.
4. Divide by 4: that is your daily dose for the week.
5. Retest weekly and adjust.

Three rules not to skip

• Daily maximums: calcium 20ppm, alkalinity 0.5 meq/l (1.4 dKH), magnesium 10ppm.
• Dosing order: magnesium, then alkalinity, then calcium — 10 minutes between each.
• Where to add it: into the sump, or slowly into a high-flow area.

Adding calcium to saturation levels causes a sudden drop in alkalinity. The three elements hold each other up.

Which size to choose

The litre suits an established tank: enough to last months without tying up cash. For a nano or a trial run, the 500ml is plenty. For a large system or a dosing pump running continuously, the 5L costs less per litre.

Goes well with

Calcium does not work alone. Foundation B KH/Alkalinity 1L supplies the carbonates without which calcium forms no aragonite, and Foundation C Magnesium 1L keeps the two from precipitating against each other.

Frequently asked questions

How much calcium can I add in one day?

Red Sea caps it at 20ppm per day. Larger gaps are spread over several days while respecting that ceiling.

Is the 1L the same strength as the 500ml?

Yes, it is the same product: 1ml raises calcium in 100 litres by 2ppm in both. Only the volume differs. The powder version, however, has its own concentration.

My calcium will not rise despite dosing — why?

Red Sea lists three causes: new aragonite substrate precipitating calcium and carbonates, an unbalanced salt mix (low magnesium or high calcium), or excess buffer added while calcium was already at saturation. Test magnesium before dosing more.

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. We ship across Canada and offer in-store pickup.