Mad Farmer Cal+Mag – 6 Gallon

Mad Farmer Cal+Mag is a liquid calcium, magnesium, and iron supplement formulated for growers who rely on reverse-osmosis water or coco coir media. These growing conditions naturally strip or lack the secondary nutrients that plants need for structural development, enzyme activation, and chlorophyll production. Cal+Mag delivers those nutrients in readily available forms — calcium nitrate, magnesium nitrate, and iron EDTA — without dyes or fillers, and it is compatible with any nutrient program or growing medium. This listing covers the 6-gallon container, sized for commercial operations and large indoor gardens running continuous feeding schedules.

Mad Farmer Cal+Mag – 6 Gallon Specifications

The table below lists confirmed specifications drawn from the manufacturer description and shipping attributes.

Specification	Value
Brand	Mad Farmer
Product Name	Cal+Mag
SKU	MFCALMAG6G
Container Volume	6 Gallon (approx. 22.7 L)
Product Form	Liquid concentrate
Shipping Weight	57.85 lb (26.24 kg)
Primary Ingredients	Calcium Nitrate, Magnesium Nitrate, Iron EDTA
Dyes / Colorants	None
Application Methods	Nutrient solution feed; foliar spray
Compatible Growing Media	Hydroponics, coco coir, soil
Recommended Use Frequency	With every feeding

Why Choose Mad Farmer Cal+Mag

Calcium and magnesium are frequently the first nutrients to fall short in modern growing systems. RO water removes essentially all dissolved minerals before it reaches your reservoir, and coco coir — while an excellent medium for root development and drainage — has a cation exchange capacity that can tie up calcium and release it erratically, creating deficiencies even when the nutrient solution looks adequate on paper. Mad Farmer Cal+Mag was built specifically for these conditions.

The supplement uses water-soluble calcium nitrate and magnesium nitrate as its primary carriers. These forms dissolve cleanly, do not precipitate at standard reservoir temperatures, and become plant-available quickly — unlike chelated calcium, which can interact unpredictably with high-phosphorus base nutrients. Iron EDTA, a well-established chelated iron form, rounds out the formula and supports chlorophyll synthesis without competing with calcium or magnesium at the root zone.

• No dyes or colorants. The formula contains no added dyes, so it does not stain growing media, irrigation lines, or dripper heads over time. This matters in large commercial installations where maintenance downtime has a real cost.
• Broad medium compatibility. Cal+Mag is labelled for use in hydroponics, coco coir, and soil systems. The same concentrate works whether you are running a recirculating deep water culture setup, a drain-to-waste coco slab farm, or an amended living soil bed.
• Supports blossom end rot prevention. Calcium deficiency during fruit set is the primary cause of blossom end rot in fruiting crops. Maintaining consistent calcium levels through bloom and ripening with Cal+Mag reduces the incidence of this disorder.
• Foliar application supported. The manufacturer specifies a foliar rate of 5 mL per quart, giving growers a fast-response option when visible deficiency symptoms appear between reservoir changes. Foliar absorption typically acts within 24–48 hours, ahead of root-zone correction.
• 6-gallon format reduces per-unit cost. At commercial feeding rates, the 6-gallon container provides enough concentrate for thousands of gallons of finished nutrient solution. Buying at this volume lowers the cost per litre compared to quart or single-gallon formats and reduces packaging waste.

Best Uses for Mad Farmer Cal+Mag

Cal+Mag is designed as a general-purpose supplement that runs alongside your base nutrient program throughout the entire crop cycle, with dose adjustments at key stages. The following use cases represent the most common applications described in the manufacturer documentation.

• RO water systems. Reverse-osmosis filtration removes the naturally occurring calcium and magnesium from source water, leaving a near-zero baseline. Cal+Mag is the standard way to rebuild this mineral foundation before adding base nutrients. Without it, plants grown on RO water will show magnesium deficiency (interveinal chlorosis) and calcium deficiency (tip burn, distorted new growth) within weeks.
• Coco coir growing media. Coco coir has a high cation exchange capacity and actively absorbs calcium ions from solution. New coir must be pre-buffered with calcium and magnesium before planting, and ongoing supplementation through the grow cycle prevents deficiencies from reappearing as the medium’s exchange sites gradually saturate. Cal+Mag is an efficient tool for both pre-buffering and regular maintenance feeding in coco.
• Transitioning into and through bloom. Calcium demand rises sharply during the transition from vegetative growth to flowering, when cell wall formation accelerates to support developing flower structures and, later, fruit set. The graduated dosing table in the Cal+Mag directions — from 5 mL/gallon in vegetative up to 15 mL/gallon during blooming and ripening — reflects this increased demand and gives growers a concrete schedule to follow rather than guessing from symptom observation.
• Foliar deficiency correction. When visible calcium or magnesium deficiency symptoms appear — yellowing between leaf veins, brown leaf tips, or distorted young leaves — a foliar application at 5 mL per quart delivers nutrients directly to the affected tissue while a root-zone correction takes effect. This dual-track approach is faster than adjusting reservoir concentration alone and can prevent further crop loss while systemic levels catch up.
• Commercial production at scale. The 6-gallon container is sized for operations that go through multiple litres of Cal+Mag per week. Large DWC systems, NFT tables, and commercial coco greenhouse grows running multi-strain cultivation tables benefit from having a bulk supply on hand to maintain consistent feed parameters without weekly re-ordering.

Mad Farmer Cal+Mag vs Similar Cal-Mag Supplements

The cal-mag supplement category is well-stocked, and most products in it accomplish the same basic task: delivering calcium and magnesium in water-soluble form. The practical differences between brands come down to ingredient choices, secondary additions, and formulation specifics.

Many cal-mag products on the market add nitrogen (typically 2–5% total nitrogen) along with the calcium and magnesium. This makes them convenient for vegetative feeding but can create nitrogen excess if the grower needs to push calcium intake during late bloom without adding more nitrogen to the program. Mad Farmer Cal+Mag uses calcium nitrate and magnesium nitrate as its vehicles, meaning some nitrogen is inherent in the formula, but the manufacturer does not publish a guaranteed analysis NPK breakdown in the available documentation. Growers running tight nitrogen windows in late flower should account for this when building their feed chart.

The dye-free distinction separates Cal+Mag from several competing products that include blue or green colorants. In a commercial setting with multiple pumps, reservoirs, and irrigation lines, dye-free concentrates simplify maintenance and reduce staining of light-colored growing systems and equipment. If you are also running a root-health programme, consider pairing Cal+Mag with a root stimulant like Heavy 16 Roots to support overall nutrient uptake alongside calcium and magnesium supplementation.

The 6-gallon volume itself is a meaningful differentiator. Competing products in the same category are often available only up to 2.5-gallon containers at most retail price points, which means commercial growers are paying single-pack pricing for multiple units. The Mad Farmer 6-gallon format provides comparable concentrate volume to two-plus standard jugs in a single order, lowering per-dose cost and reducing the frequency of reordering.

Compatibility

Mad Farmer Cal+Mag is described by the manufacturer as compatible with all nutrient programs and all growing mediums. The three growing system types explicitly named in the product documentation are hydroponics, coco coir, and soil.

Because Cal+Mag is a liquid concentrate that is added to the reservoir or foliar tank alongside other inputs, it functions as a nutrient-program-agnostic additive. It does not rely on proprietary chelation technology that could conflict with specific base nutrients, and its dye-free formula avoids the optical interference that coloured supplements can create when growers are using colour-change pH indicator solutions.

When building a nutrient stack, Cal+Mag should be added to the reservoir before base nutrients. Add it to plain (or RO-filtered) water first, allow it to mix, then add your base A and B solutions and any other supplements in order. This prevents localised high-concentration zones where calcium could react with phosphate ions in base nutrients before adequate dilution has occurred. For growers looking to support the complete nutrient ecosystem, a carbohydrate supplement like Earth Juice Hi-Brix Molasses can be added to feed beneficial microbial populations in soil and coco systems that are already receiving Cal+Mag.

For foliar applications, use fresh water that has been pH-adjusted to approximately 6.0–6.5. Spray in the early morning or evening to minimise evaporation and reduce the risk of leaf scorch under direct grow-light exposure. Cal+Mag foliar applications are compatible with standard pump sprayers and electrostatic applicators.

Dosing Guidelines

The following dose rates are taken directly from the manufacturer documentation. All rates are per gallon of prepared nutrient solution or spray solution unless otherwise noted. Measure with a calibrated syringe or graduated measuring cup — volumetric accuracy matters more in small reservoirs where even a 1 mL error per gallon can shift the calcium contribution by 20% or more.

Growth Stage / Application	Dose Rate	Equivalent
Cuttings / Seedlings	1–2 mL per gallon	¼–½ tsp per gallon
General Purpose	5 mL per gallon	1 tsp per gallon
Vegetative Stage	5–10 mL per gallon	1–2 tsp per gallon
Transition to Bloom	10–15 mL per gallon	2–3 tsp per gallon
Blooming and Ripening	15 mL per gallon	3 tsp per gallon
Foliar Spray	5 mL per quart	1 tsp per quart

The manufacturer recommends using Cal+Mag with every feeding as a general-purpose calcium/magnesium supplement. For growers who are also supplementing with a plant-health additive like PureCrop1, add Cal+Mag to the reservoir first before introducing other additives to avoid localised precipitation at the point of mixing.

How to Use Mad Farmer Cal+Mag

1. Shake the container before each use. Liquid nutrient concentrates can stratify during storage, especially in a 6-gallon container that may sit for extended periods between uses. Invert or agitate the jug to ensure the concentrate is evenly mixed before measuring.
2. Measure the dose with a calibrated syringe or measuring cup. Use the dose table above for your current growth stage. For cuttings and seedlings, start at 1 mL per gallon and observe plant response before moving to the higher end of the range. For mature vegetative plants and flowering crops, apply at the stage-appropriate rate listed above.
3. Add Cal+Mag to plain or RO water first. Fill your reservoir or mixing vessel with water, then add Cal+Mag and stir before introducing base nutrients or other supplements. Adding it to plain water first prevents localised high-concentration pockets where calcium and phosphate ions from base nutrients can react and precipitate out of solution.
4. Add remaining nutrients in your standard order. After Cal+Mag is fully mixed, add your base nutrient Part A and Part B (keeping them separate until diluted), followed by any other additives in your programme. Mix thoroughly after each addition.
5. Adjust pH to target range. After all nutrients have been added, check EC to confirm it is within your stage-appropriate range, then adjust pH to your target — typically 5.5–6.5 for hydroponic systems, 6.0–7.0 for soil. Cal+Mag does not significantly alter pH on its own at normal dose rates, but the cumulative effect of a full nutrient stack always requires pH verification before feeding.
6. For foliar applications: Mix 5 mL Cal+Mag per quart of plain water. Adjust pH to approximately 6.0–6.5. Apply using a clean pump sprayer, coating the underside of leaves where stomata are concentrated. Spray during lights-off or at the beginning and end of the photoperiod to reduce evaporation and minimise the risk of light-concentrated droplets causing leaf scorch.
7. Store the concentrate in a cool, dry location away from direct sunlight. Cap the container tightly after each use. The 6-gallon jug is heavy when full — use appropriate handling practices and store at floor level or on a low shelf.

Sources & Further Reading