CalMag Pro by Plagron – Calcium Magnesium Supplement for RO & Soft Water

CalMag Pro by Plagron is your go-to calcium and magnesium booster, specially formulated to prevent deficiencies in reverse osmosis (RO) and soft water setups—giving your plants a rock-solid foundation for explosive growth and resilience.

Struggling to figure out the right nutrient balance for your grow? You're not alone. Many growers start strong but hit a wall when their plants show yellowing leaves, weak stems, or poor nutrient uptake—only to realize too late that their water was missing essential minerals all along.

Without enough calcium and magnesium, your plants can’t build strong cell walls, absorb nutrients efficiently, or withstand stress. This silent deficiency creeps in unnoticed, sabotaging yields and leaving you frustrated. You might even think your nutrients aren’t working—when the real issue is the base water itself.

CalMag Pro is the solution. It delivers the perfect, pre-balanced ratio of calcium and magnesium in a fully soluble form, so you can create stable, pH-friendly nutrient solutions from the start. No guesswork, no mixing conflicts—just reliable, consistent results every time you water.

Why Your RO Water Needs CalMag Pro

Reverse osmosis water is pure—but that’s the problem. It strips out essential minerals like calcium and magnesium, leaving your plants vulnerable. CalMag Pro restores what’s missing, ensuring your nutrient solution starts strong and stays effective.

• Prevents Ca/Mg deficiencies that cause leaf curling, spotting, and stunted growth
• Stabilizes pH in your nutrient solution—less fluctuation, less stress
• Compatible with all nutrient lines, especially in hydro, coco and aeroponic systems

Stronger Plants, Better Nutrient Uptake

Calcium isn’t just a nutrient—it’s the glue that holds your plant’s structure together. Magnesium is the heart of chlorophyll. Together, they’re non-negotiable for healthy growth.

• Strengthens cell walls for more resilient plants
• Boosts root development and nutrient absorption
• Improves overall plant vigor and resistance to stress

Perfect for LED Growers

LED lights reduce plant transpiration, which can limit calcium uptake. That means even if it’s in your water, your plants might not get enough. CalMag Pro compensates for this by delivering highly bioavailable calcium directly to the roots—keeping your plants strong from the inside out.

How to Use CalMag Pro – Step by Step

1. Shake well before use
2. Add up to 1 ml per liter of water (1:1000 ratio)
3. Mix with your base nutrients or use in every irrigation
4. Use from seedling to harvest—especially in coco or hydro systems
5. Monitor EC—aim for 0.4 with 0.75 ml per liter for ideal starting point

Advantages of Using CalMag Pro Over DIY Solutions

• No guesswork—precise, balanced formula vs. homemade mixes
• Zero risk of clogging—fully soluble, unlike gypsum or eggshells
• pH-stable solutions mean less maintenance and more chill time
• Trusted by expert growers in hydroponic and aeroponic systems worldwide

Frequently Asked Questions

Can I use CalMag Pro as a foliar spray?

Yes, CalMag Pro works well as a foliar application to correct deficiencies quickly. Just mix at half strength and spray during low light hours.

Do I need CalMag Pro if I’m using tap water?

It depends on your water’s hardness. If you’re using soft or RO water, yes. If your tap water is hard, test your EC and mineral content first—CalMag Pro is essential when calcium and magnesium are low.

Can I use it throughout flowering?

Absolutely. CalMag Pro contains no nitrogen, so it won’t interfere with flowering. In fact, maintaining calcium levels during bloom prevents tip burn and supports dense bud development.

Is it compatible with other nutrient brands?

Yes, CalMag Pro is designed to work seamlessly with all major nutrient lines, including Canna, Hesi, GHE, and BioBizz.

Personal Experience of Pevgrow’s CEO (Alan)

I’ve used CalMag Pro since my first serious hydroponic run, and it’s been a game-changer. Early on, I struggled with weak stems and mysterious leaf spots—turned out my RO system was giving me pure water, but not the right kind of pure. I tried Epsom salt and garden lime, but the pH went wild and my pumps clogged. Once I switched to CalMag Pro, everything stabilized. Now I use it in every grow, especially with LEDs. I dose at 0.75 ml/L from week one, and I’ve never had a Ca/Mg deficiency since. It’s simple, effective, and worth every penny. If you’re running RO or coco, this isn’t optional—it’s essential.