The amount of grain spawn required to refill a monotub depends on the size of the tub and the ratio of spawn to bulk substrate you’re using. Here’s a general guideline for common monotub sizes:
- Small Monotub (e.g., 20-quart):
- Typically requires 2-3 pounds of grain spawn.
- Use with 4-6 pounds of bulk substrate for a 1:2 or 1:3 spawn-to-substrate ratio.
- Medium Monotub (e.g., 50-quart):
- Typically requires 5-6 pounds of grain spawn.
- Use with 10-15 pounds of bulk substrate for a 1:2 or 1:3 ratio.
- Large Monotub (e.g., 66-quart or larger):
- Typically requires 7-10 pounds of grain spawn.
- Use with 15-20 pounds of bulk substrate for a 1:2 or 1:3 ratio.
General Guidelines
- 1:2 Ratio: One part spawn to two parts substrate is ideal for quicker colonization and reduced contamination risk.
- 1:3 Ratio: This works well for maximizing bulk substrate while still maintaining good colonization speed.