Aptus MINERAL-CALMAG, 20 L

Buffer Your Feed Water and Prevent Ca-Mg Deficiencies in Soil-Less Systems, 20 L

Soil-less growing mediums such as coco coir, perlite, rockwool, and hydroton offer precise control over the root environment, but that control comes at a cost: the medium provides no natural mineral buffering and often strips calcium and magnesium from the feed solution before the plant can access them. Mineral-CalMag is a 100% water-soluble calcium, magnesium, and nitrogen supplement formulated to prevent Ca-Mg deficiencies while also stabilizing feed water pH.

Mineral-CalMag ships in a 20 L container, sized for commercial growers running a recirculating or fertigation system.

Key Features & Benefits

• 100% water-soluble Ca-Mg-N formula — delivers calcium, magnesium, and nitrogen in fully plant-available forms without residue or precipitate.
• pH stabilizing capability — buffers feed water to reduce the pH drift common in recirculating and fertigation systems over extended reservoir holds.
• Prevents Ca-Mg deficiencies in soil-less media — formulated specifically for coco, perlite, rockwool, hydroton, and recirculating hydroponic systems.
• Scales with water source — dosage adjusts from 1.5 ml per gallon with a 2-part NPK up to 3-4 ml per gallon with RO or soft water.
• Fits fertigation and long reservoir holds — suited to commercial cultivators running fertigation or recirculating systems that need stable Ca-Mg and pH over extended intervals.

Who Should Use Aptus Mineral-CalMag

Growers running soil-less systems such as coco, perlite, rockwool, or recirculating hydro who need reliable Ca-Mg supplementation and feed water pH stability, particularly those using RO or soft water or running long reservoir holds, with the 20 L size matched to system scale.

About Aptus Mineral-CalMag

Aptus Plant Tech began developing soil- and plant-science-based nutrient research in the Netherlands in the 1990s and has grown into a hydroponic nutrient supplier distributing across Europe, North America, and Australia. Mineral-CalMag doses at 1.5 ml per gallon with a two-part NPK, 2.5 ml per gallon with Aptus Liquid Base and municipal water, or 3-4 ml per gallon with Liquid Base and RO or soft water, and is one of the two approved calcium sources for Liquid Base alongside Massboost.

Frequently Asked Questions

Can Mineral-CalMag be used as the sole calcium source alongside Aptus Liquid Base?

Yes, it's one of the two approved Ca sources for Liquid Base, the other being Massboost. It can be used throughout both vegetative and flowering stages as a continuous Ca-Mg supplement.

Why does dosage change depending on the water source?

RO and soft water contain fewer dissolved minerals, so the feed solution needs more buffering from Mineral-CalMag to provide stable Ca and Mg levels. Municipal water already contains some calcium and magnesium hardness, so a lower dose is appropriate.

How does Mineral-CalMag stabilize pH?

Its dissolved mineral profile buffers the pH of the feed solution, reducing drift over time, particularly valuable in recirculating and fertigation systems where the reservoir can shift pH between top-offs. That stability is what makes it suited to longer reservoir holds.

When should I dose Mineral-CalMag versus Massboost?

Mineral-CalMag is dosed continuously through both vegetative and flowering stages, while Massboost is applied at specific weeks (3, 5, and 7) during flower. Growers choose one as their primary Ca-Mg source for a Liquid Base program based on whether they want continuous or week-targeted delivery.