Botanicare 2.5gal Cal-Mag Plus (2/CS)

Botanicare Cal-Mag Plus (2-0-0) is a concentrated liquid calcium, magnesium, and iron supplement formulated to correct common secondary nutrient deficiencies. This 2.5-gallon case pack (2 bottles per case) is designed for commercial growers and large-scale operations that need to supplement their base nutrient program — particularly when working with reverse osmosis water or coco coir growing media where calcium and magnesium depletion is a known factor.

Cal-Mag Plus Specifications

The following table summarizes the key product specifications for Botanicare Cal-Mag Plus 2-0-0 in the 2.5-gallon case format (2/CS).

Why Choose Cal-Mag Plus

Calcium and magnesium are secondary macronutrients that plants consume in relatively large quantities, yet many base nutrient programs and water sources do not supply enough of them to prevent deficiency — especially under demanding grow conditions. Cal-Mag Plus addresses this directly:

• Formulated for known deficiency scenarios. The 2-0-0 formula is built around calcium, magnesium, and iron — the three nutrients most commonly depleted when using stripped-mineral water sources or high-absorption substrates like coco coir.
• Recommended for reverse osmosis systems. RO filtration removes most dissolved minerals, including calcium and magnesium. Adding Cal-Mag Plus restores these elements before mixing the rest of the nutrient solution.
• Addresses natural calcium draw in coco coir. Coco coir has a documented tendency to bind calcium ions, making them temporarily unavailable to roots. Supplementing with Cal-Mag Plus compensates for this draw and keeps plants from showing deficiency symptoms during the vegetative and early flower stages.
• Dual-application flexibility. Cal-Mag Plus can be mixed directly into a reservoir or applied as a foliar spray, giving growers the option to address acute deficiency symptoms quickly through leaf absorption while continuing reservoir supplementation as a preventive measure.
• Supplements any base nutrient line. The product is designed to work alongside any existing nutrient program rather than replacing it, so growers do not need to change their base schedule when adding Cal-Mag Plus.

Best Uses for Cal-Mag Plus

Cal-Mag Plus is a widely-used secondary nutrient supplement in controlled-environment agriculture. The following situations are where it is most commonly applied:

• Reverse osmosis water systems. Any grower running RO filtration should treat their water with a calcium-magnesium supplement before building their nutrient solution. Cal-Mag Plus is a standard first step in this process.
• Coco coir grows. Coco-based media is popular for its drainage and aeration properties, but its calcium-binding behavior makes ongoing Cal-Mag supplementation a standard practice rather than an optional one.
• Hydroponic and soilless systems. In rockwool, perlite, or other inert media where the substrate contributes no mineral buffering, the nutrient solution is the plant’s only source of calcium and magnesium. Cal-Mag Plus helps maintain adequate levels throughout the crop cycle.
• Correcting active deficiencies via foliar spray. When plants show interveinal chlorosis or leaf curl consistent with calcium or magnesium shortage, a foliar application delivers these nutrients directly to affected tissue while the reservoir solution continues building reserves at the root zone.
• Large-scale commercial operations. The 2.5-gallon case pack (2/CS) format reduces the frequency of reordering and is well-suited to facilities running multiple reservoirs or large recirculating systems that go through supplements quickly. If you are also managing your root zone health, see Heavy 16 Roots 55-gallon for a large-format root supplement option.

Dosing Guidelines

Cal-Mag Plus is a concentrated liquid supplement. General guidance for reservoir supplementation is to add it before other nutrient concentrates so calcium and magnesium are fully dissolved and available when the pH is adjusted.

• Shake or stir the concentrate before measuring to ensure uniform consistency.
• Measure the recommended dose per gallon or litre using a calibrated syringe or measuring cup. Refer to the Botanicare feeding chart for the specific dose rate appropriate to your growth stage — dosing information is published at botanicare.com.
• Add Cal-Mag Plus to your reservoir or foliar-spray tank first, then add base nutrients, then adjust pH to your target range (typically 5.8–6.2 for hydroponic systems).
• Verify EC is within the target range for the growth stage after mixing. Adjust dose based on plant response and runoff EC over time.
• For foliar application, dilute to a lower concentration than reservoir rates and spray during lights-off or low-light periods to avoid leaf burn.
• When using Cal-Mag Plus alongside other supplements such as Advanced Nutrients Tarantula for microbial root support, confirm each product’s pH impact and add them in the order that minimizes pH swing.

Sources & Further Reading