How do I identify contamination in my grow?

Common contaminants appear as green, black, pink, or orange patches (mold) or slimy wet areas (bacterial contamination). Healthy mycelium is always white to off-white; any other coloration is a warning sign requiring immediate isolation.

Can I save contaminated grain spawn?

Contaminated grain spawn should generally be discarded and double-bagged immediately to prevent spore spread. Attempting to salvage contaminated grain rarely succeeds and risks spreading contamination to other grows.

How can I prevent contamination?

Working in a still-air box or laminar flow hood, using properly sterilized equipment, and maintaining good personal hygiene (gloves, mask, disinfected surfaces) dramatically reduces contamination rates. Keeping humidity high but air exchange adequate also helps prevent bacterial wet rot.

Contamination Prevention Checklist

1. Personal Hygiene

Shower & Brush Teeth
You are the biggest source of contamination. Clean your body and mouth.
Wear Fresh Clothes
Put on clean clothes straight from the dryer. Short sleeves are better (less fabric to drag).
Tie Back Hair / Wear Hat
Loose hair and dandruff are major vectors.
Wear a Mask
Do not breathe on your work. Even a surgical mask helps immensely.
Gloves + Alcohol
Wear nitrile gloves and wipe them with 70% ISO frequently.

2. Workspace Preparation

Close Windows & Doors
Stop all drafts. Turn off fans, AC, and heaters 1 hour before starting.
Clear the Surface
Remove clutter. Wipe down the table/desk with disinfectant.
Prepare the SAB
Wipe the inside of your Still Air Box with soapy water or ISO. Mist the air inside lightly to trap dust.
Remove Pets
Cats and dogs are walking contamination factories. Keep them out.

3. Tool Management

Flame Sterilize
Heat needles/scalpels until red hot before EVERY jar/plate.
Cool Before Touching
Hot tools kill spores/mycelium. Cool the tool on sterile agar or in the air for 10s.
Don't Reach Over
Never move your hand over an open jar or plate. Particles fall from your arm.

4. Sterilisation Reference Table

Different materials require different sterilisation methods. Using the wrong method is a leading cause of contamination failure:

Material	Method	Temp/Pressure	Duration
Grain spawn (rye/oats/WBS)	Pressure cooker	15 PSI / 121°C	90 minutes
BRF (brown rice flour) cakes	Steam sterilise or pressure cook	100°C steam / 15 PSI	60-90 minutes
Agar media (PDA/MEA)	Pressure cooker	15 PSI / 121°C	20-30 minutes
Coco coir bulk substrate	Pasteurise (boiling water)	70-80°C	60-90 minutes covered
Metal tools (scalpels, needles)	Flame + 70% IPA wipe	Red hot flame	5-10 seconds flame, cool before use
Work surfaces	70% IPA wipe + Lysol (no aerosol near open substrate)	N/A	Let dry fully before opening substrate

5. Still Air Box (SAB) Best Practices

A Still Air Box is a clear plastic storage bin or tote with two arm holes cut in the front. When used correctly, it dramatically reduces airborne contamination during inoculation. Common mistakes that defeat its purpose:

Mist the interior before use
A light mist of water inside the SAB weighs down airborne particles. Wait 5-10 minutes after misting before starting work.
Do not breathe into the box
Keep your face well away from the arm holes. Breath carries enormous numbers of airborne microbes. Turn your head to the side when you need to breathe.
Move slowly
Fast arm movements create turbulence inside the box, stirring up particles that had settled. Move deliberately and slowly at all times.
Organise everything before starting
Have all tools, jars, and syringes laid out and ready inside the SAB before you begin. Repeated arm insertions break the still air environment.

6. Factors That Influence Contamination Rate

Understanding what drives contamination allows you to prioritise your prevention efforts. Not all factors are equally important:

Sterilisation failure (highest risk): Under-sterilised grain is the single most common cause of contamination. Pressure cooking duration and starting pressure both matter — ensure 15 PSI is reached before timing begins.
Inoculation technique (high risk): Contamination introduced during inoculation is the second most common cause. Still air box or flow hood usage, flame sterilisation of needles, and not breathing on open substrate are all critical.
Room cleanliness (medium risk): Dusty, mouldy rooms with pets have far higher ambient spore counts. Clean and HEPA-filter your grow space if possible.
Humidity management (medium risk): Too-high humidity without adequate airflow creates ideal conditions for bacterial wet rot, especially in summer when ambient temperatures are high.
Genetics/strain (low-medium risk): Some strains (PE variants) have slower colonisation rates, which extends the contamination vulnerability window. Fast strains (Cambodian, GT) are naturally more resistant.