BioBizz Calmag - Organic Calcium and Magnesium Supplement
Best for: growers using soft water, reverse osmosis or coco coir who need to top up calcium and magnesium without upsetting an organic feeding schedule.
Our thoughts
Calcium and magnesium deficiencies are one of the most common problems growers run into once they switch to RO water or coco, and this fixes it without dragging synthetic salts into an otherwise organic grow. It's a genuinely useful bottle to keep on the shelf rather than a nice-to-have.
BioBizz Calmag is a 100% organic, certified calcium and magnesium supplement built for growers whose water source or growing medium doesn't supply enough of either element on its own, most commonly reverse osmosis water, very soft tap water, or coco coir, which naturally locks up calcium and magnesium. Because it's formulated without nitric acid and carries no added nitrogen, it doesn't shift the NPK balance or EC of your existing feed, so you can dose it alongside your normal nutrient schedule without having to rework anything.
It's designed to sit on top of whatever base feed you're already running rather than replace it, correcting the specific deficiency without adding extra complexity to your mix.
How it compares
Cal-mag supplements are a near-universal add-on across every nutrient brand, and BioBizz's version stands out mainly on its organic certification.
- Vs Emerald Harvest Cal-Mag: Emerald Harvest's version is a mineral-salt formula (calcium nitrate, magnesium sulfate) with a small NPK contribution, whereas BioBizz Calmag is certified organic and contributes no nitrogen at all.
- Vs Canna's Cannazym or Cal-mag lines: Canna's mineral cal-mag products are widely used in coco setups but aren't organic-certified.
- Vs General Hydroponics CALiMAGic: a mineral product aimed at the same coco and RO-water deficiency, priced similarly but without organic certification.
If you're running an organic grow and need a cal-mag top-up that won't compromise it, this is one of the few certified-organic options on the market, at a similar price to the mineral alternatives.
Usage guidance
Dosage depends on your growing medium, since coco and hydro setups typically need more than soil.
Hydroponics and coco coir
Use 0.5 to 1ml of Calmag per litre of water, mixed in with your regular feed.
Soil
Use a lighter dose of 0.3 to 0.8ml per litre of water, since soil generally holds and buffers calcium and magnesium better than coco or hydro media.
When to use it
Watch for the classic signs of deficiency, rusty spotting on lower leaves for magnesium, or stunted new growth and weak stems for calcium, and dose preventatively if you're on RO water or running coco from the start.
Technical specifications
- Certification: 100% organic
- Nitrogen content: none added (won't shift NPK or EC)
- Formulated without: nitric acid
- Dosage (hydro/coco): 0.5-1ml per litre
- Dosage (soil): 0.3-0.8ml per litre
- Sizes available: 250ml, 500ml, 1L, 5L, 10L
- Vendor: BioBizz (Netherlands)
Who this is for
- Growers using reverse osmosis or very soft tap water
- Coco coir growers needing to counter calcium and magnesium lock-up
- Organic growers who don't want a mineral-salt cal-mag product in the mix
- Anyone seeing early signs of cal-mag deficiency and wanting a quick, targeted fix
Best suited to coco and RO-water grows where cal-mag deficiency is a when-not-if problem.
Our take
This is a genuinely useful supplement rather than an upsell: if you're on RO water or coco, you will need calcium and magnesium from somewhere, and this gets it done without adding synthetic salts to an organic feed.
One we sell a lot of for new growers moving into coco for the first time.
