THC Cal-Mag | Calcium & Magnesium Supplement for LED Grows, Coco & RO Water

THC Cal-Mag is a calcium and magnesium supplement formulated for modern grow environments where deficiencies are increasingly common. High PAR LED lighting pushes plants harder than HPS ever did — increasing photosynthetic rates, accelerating nutrient demand, and exposing the calcium and magnesium shortfalls that come with RO water, coco coir, and soft water systems.
The result is tip burn, interveinal yellowing, weak structure, and nutrient imbalance that limits what your plants can actually achieve.

THC Cal-Mag restores Ca and Mg levels to stabilise plant function, strengthen cell structure, and support efficient light utilisation under high-intensity conditions. Essential mineral-based, PGR-free, and compatible with hydroponics, coco coir, and soil.

Key Benefits

• Corrects calcium deficiency — eliminates tip burn and strengthens cell walls
• Corrects magnesium deficiency — reverses interveinal yellowing and restores photosynthesis
• Essential for LED, RO water, and coco coir setups where Ca/Mg is consistently low
• Raises and stabilises EC for more consistent nutrient delivery
• Improves uptake efficiency of all other nutrients in the solution
  

How It Works

Calcium builds cell walls and supports root tip and new growth integrity — without it, stems weaken and tips burn. Magnesium sits at the centre of the chlorophyll molecule, driving photosynthesis, light energy capture, and enzyme activation.
Under high PAR LED, demand for both minerals increases faster than most base programs or water sources can supply. Cal-Mag also stabilises EC and ion exchange in the root zone, preventing the nutrient lockout that follows an imbalanced solution.

How to Use

Add to your nutrient solution throughout all growth stages, or apply at first signs of deficiency. Add before base nutrients if required to ensure proper mixing. Works across DWC, NFT, coco, and soil.

If you're running RO water, coco coir, or high-intensity LED lighting — Cal-Mag isn't optional. These three factors consistently deplete calcium and magnesium faster than standard programs account for.

THC Cal-Mag is a foundational supplement for modern grow systems — not an afterthought. Get your Ca and Mg right and everything else in your feed program works better.

Frequently Asked Questions

How do I add THC Cal-Mag to my feeding program?

Add THC Cal-Mag to your nutrient solution after mixing your base nutrient. Always add additives to water rather than directly to concentrated nutrient solutions. Stir well after each addition and check EC and pH before use. Start at the lower end of the recommended dose range and increase progressively — additives are potent and more is not always better.

Is THC Cal-Mag compatible with organic and mineral nutrient programs?

THC Cal-Mag is compatible with most hydroponic nutrient programs including both mineral and organic-based systems. If running a fully organic or biological program, check the formulation — some mineral additives can inhibit beneficial microbial populations. When in doubt, contact us at hello@apexgrow.com.au for compatibility advice specific to your setup.

Can I use THC Cal-Mag in soil, coco, and hydro?

Yes — THC Cal-Mag is suitable for use across all growing mediums including soil, coco coir, perlite, rockwool, and all recirculating and run-to-waste hydroponic systems. Dose rates may vary slightly between growing systems — always follow the manufacturer's feeding chart for your specific medium.

Does THC Cal-Mag ship fast within Australia?

Yes — THC Cal-Mag ships from our Australian warehouse with fast tracked delivery Australia-wide. Most east coast orders arrive within 2–5 business days. WA, NT, and TAS orders typically arrive within 5–12 business days.