Agricultural-Grade Calcium Carbonate

Pure Mineral Buffering. Zero Chemical Processing.

Acidic substrates can quietly sabotage healthy microbial activity and mushroom production long before contamination becomes visible.

This natural, agricultural-grade Calcium Carbonate (CaCO₃) is mechanically sifted through a precision Mesh #16 screen at the STS to provide a consistent, slow-release pH buffer for mushroom cultivation, vermiculture and biological growing systems.

Unlike hydrated lime (Calcium Hydroxide), Calcium Carbonate acts gradually, helping maintain a stable growing environment without causing sudden alkaline shocks to sensitive biology.

🛠 Technical Specifications

Product: Natural Agricultural Calcium Carbonate

Chemical Formula: CaCO₃

Particle Size: Mesh #16 Precision Sifted

Grade: Agricultural

Net Weight: 500 g

Packaging: Resealable Stand-Up Pouch

🍄 Why Mushroom Growers Use Calcium Carbonate

Slow-Release pH Buffer

Calcium Carbonate gradually neutralises excess acidity, helping maintain a stable substrate environment throughout colonisation.

Unlike fast-acting alkaline products, it works slowly, making it far more forgiving when preparing mushroom substrates.

CVG & Bulk Substrates

Ideal when preparing:

• Coco Coir
• CVG mixes
• Compost-based substrates
• Supplemented hardwood substrates

Typical application:

1–2% of dry substrate weight

Grain Spawn

May be incorporated into grain formulations where additional buffering is desirable. Also added in Sinden Grain Spawn to act as a ‘lubricant’ prevent clumping of grain – apply at 1-2% if dry grain mass.

🪱 Vermiculture & Compost

Excellent for worm bins where acidic feedstocks such as fruit waste and coffee grounds gradually lower bedding pH.

Use to:

• Buffer acidic bedding
• Stabilise biological activity
• Maintain healthy worm populations
• Reduce “sour” conditions caused by overfeeding

🧫 Agar Media

A small pinch may be incorporated into agar formulations when preparing media intended for organisms that prefer neutral pH conditions.

Maintaining adequate buffering capacity helps reduce excessive acidification during media preparation. Agar agar may not fully set under acidic conditions, preventing Petri dishes from being safely inverted. Add a small pinch of Calcium Carbonate per litre of media when buffering is advised.

✔ STS Mesh #16 Precision Sifted

Every batch is mechanically screened for a consistent particle size that blends uniformly through substrates and bedding.

Benefits include:

• Uniform mixing
• Consistent buffering
• Reduced dust
• Professional-quality preparation

🌱 100% Natural Origin

This product is a naturally occurring agricultural limestone.

It is:

• Unrefined
• Non-precipitated
• Free from construction additives
• Free from anti-caking agents
• Suitable for biological growing systems

⚠ Not Hydrated Lime

Natural Calcium Carbonate should not be confused with:

• Calcium Hydroxide (Hydrated Lime)
• Quicklime (Calcium Oxide)
• Builder’s Lime
• Construction Lime

Each serves a different purpose in biological cultivation.

📦 Package Includes

• 500 g Natural Calcium Carbonate (CaCO₃)
• Mesh #16 Precision Sifted
• Resealable Stand-Up Pouch

• Agar Media: add a pinch to your agar media mix when preparing, to prevent low pH conditions, Agar Agar does not set in low pH conditions.

500 gram Packaged in Stand-up Pouch.