imported>Claude: Batch 2: spores, cloning, culture storage, smash tek, drying, local suppliers; convert sources to footnotes

2026-10-22T20:00:00Z

Batch 2: spores, cloning, culture storage, smash tek, drying, local suppliers; convert sources to footnotes

← Older revision		Revision as of 20:00, 22 October 2026
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	At 6,000 ft the air supplies only about 11.8 psi. The same 15 psi weight gives about 26.8 psi total, and the steam only reaches about 244°F.		At 6,000 ft the air supplies only about 11.8 psi. The same 15 psi weight gives about 26.8 psi total, and the steam only reaches about 244°F.

	Six degrees sounds small, but heat-resistant bacterial spores die exponentially with temperature. ~~A common rule from sterilization science is~~ that every 10°C (18°F) drop means ~~you need~~ about ten times as long for the same kill. A 3.3°C drop ~~works out to~~ roughly '''twice the time''' for the ~~same~~ level ~~of sterility~~.		Six degrees sounds small, but heat-resistant bacterial spores die exponentially with temperature. Sterilization calculations conventionally assume that every 10°C (18°F) drop means about ten times as long for the same kill.<ref name="zvalue">Wikipedia, [https://en.wikipedia.org/wiki/Z-value_(temperature) "Z-value (temperature)"]: the F<sub>0</sub> sterilization measure is calculated using a z-value of 10 °C.</ref> By that rule, a 3.3°C drop means roughly '''twice the time'''. Real spores are often somewhat less sensitive to temperature than the convention assumes. A commercial test batch of the standard sterilization test organism measured a z-value near 20°C,<ref>Terragene, [https://www.terragene.com/wp-content/uploads/COA/biologico/BT20/2021/COA%20BT20.05%20-%20VAB032021.pdf certificate of analysis for ''Geobacillus stearothermophilus'' ATCC 7953 biological indicators] (D<sub>121°C</sub> 2.3 min, z 19.8 °C).</ref> which works out to about 1.5 times as long. So plan on '''1.5 to 2 times''' the sea-level time.

	== The numbers ==		== The numbers ==
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	\| 9,000 ft (above Woodland Park) \|\| 10.5 psi \|\| 195°F \|\| 241°F \|\| 19.2		\| 9,000 ft (above Woodland Park) \|\| 10.5 psi \|\| 195°F \|\| 241°F \|\| 19.2
	\|}		\|}
	Values calculated from the standard atmosphere and water's steam table; real cookers vary a degree or two.		Values calculated from the standard atmosphere and water's steam table; real cookers vary a degree or two.<ref>Calculated by the wiki editors from the U.S. Standard Atmosphere (air pressure by elevation) and the Antoine equation for water (boiling point by pressure).</ref>

	== What to do about it ==		== What to do about it ==
	=== Option 1: add pressure (dial-gauge cookers) ===		=== Option 1: add pressure (dial-gauge cookers) ===
	If your cooker has a dial gauge and an adjustable vent, run it at about '''18 psi''' around Colorado Springs and keep sea-level times. Check your cooker's manual for its maximum safe pressure first. Have the dial gauge tested periodically; county extension offices often do this.		If your cooker has a dial gauge and an adjustable vent, run it at about '''18 psi''' around Colorado Springs and keep sea-level times. Canning guidance takes the same approach, raising dial-gauge pressure with elevation instead of adding time.<ref name="nmsu" /> Check your cooker's manual for its maximum safe pressure first. Have the dial gauge tested periodically; county extension offices often do this.

	=== Option 2: add time (weighted cookers) ===		=== Option 2: add time (weighted cookers) ===
	~~Most~~ hobby cookers~~, including the popular Presto and All American models, use~~ a weighted regulator ~~that tops out at~~ 15 psi. ~~You~~ cannot add pressure~~, so~~ add time instead.		Many hobby cookers run on a weighted regulator whose heaviest setting is 15 psi. Canning guides keep the 15 lb weight at every elevation above 1,000 ft,<ref name="nmsu">NMSU Cooperative Extension, [https://losalamos-extension.nmsu.edu/documents/pressure-canning-at-high-altitudes-2.pdf "Pressure Canning at High Altitudes"].</ref> which means you cannot add pressure; add time instead.

	{\| class="wikitable"		{\| class="wikitable"
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	\|}		\|}

	~~The doubling rule is~~ the ~~conservative end~~; sea-level times already include some safety margin, which is why many local growers get away with less. If you're seeing [[Reference/Contamination#Bacteria\|bacterial contamination]] in grain, longer cook times are the first thing to try.		These times sit within the 1.5–2× range explained above; sea-level times already include some safety margin, which is why many local growers get away with less. If you're seeing [[Reference/Contamination#Bacteria\|bacterial contamination]] in grain, longer cook times are the first thing to try.

	Time starts when the weight begins to jiggle or rock steadily, not when you turn on the burner.		Time starts when the weight begins to jiggle or rock steadily, not when you turn on the burner.
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	Bulk substrates are pasteurized, not sterilized, at about 150–170°F. Water boiling at 201°F is still well above that, so pasteurization techniques like the [[Tutorials/Substrate/Coir and CVG\|bucket tek]] work fine at altitude without adjustment.		Bulk substrates are pasteurized, not sterilized, at about 150–170°F. Water boiling at 201°F is still well above that, so pasteurization techniques like the [[Tutorials/Substrate/Coir and CVG\|bucket tek]] work fine at altitude without adjustment.

	== ~~Sources~~ ==		== References ==
	* NMSU Cooperative Extension, [https://losalamos-extension.nmsu.edu/documents/pressure-canning-at-high-altitudes-2.pdf Pressure Canning at High Altitudes]: dial-gauge pressure increases by altitude, and why weighted gauges stay at 15 lb above 1,000 ft		<references />
	* Temperatures computed from the U.S. Standard Atmosphere and the Antoine equation for water

	{{Cultivation}}		{{Cultivation}}

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Wiki rebuild: cleanup and new cultivation articles

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'''Short version:''' at Colorado Springs elevations, a pressure cooker on a 15 psi weight runs about 6°F cooler than the same cooker at sea level. Sea-level recipes that say "30 minutes" or "90 minutes" assume that extra heat. Either add pressure, if your cooker can, or add time.

== Why altitude matters ==
A pressure cooker's gauge or weight measures pressure ''above the surrounding air''. The temperature inside depends on the ''total'' pressure: the air pressure outside plus what the cooker adds.

At sea level the air supplies about 14.7 psi, so a 15 psi weight gives roughly 29.7 psi total and steam at about 250°F (121°C). That is the temperature lab sterilization standards are built around.

At 6,000 ft the air supplies only about 11.8 psi. The same 15 psi weight gives about 26.8 psi total, and the steam only reaches about 244°F.

Six degrees sounds small, but heat-resistant bacterial spores die exponentially with temperature. A common rule from sterilization science is that every 10°C (18°F) drop means you need about ten times as long for the same kill. A 3.3°C drop works out to roughly '''twice the time''' for the same level of sterility.

== The numbers ==
{| class="wikitable"
|+ Steam temperature with a 15 psi weight
! Elevation !! Air pressure !! Water boils at !! Inside cooker at 15 psi !! Gauge psi needed to match sea level
|-
| Sea level || 14.7 psi || 212°F || 250°F || 15.0
|-
| 4,000 ft || 12.7 psi || 204°F || 246°F || 17.1
|-
| 5,000 ft || 12.2 psi || 202°F || 245°F || 17.5
|-
| 6,000 ft (Colorado Springs) || 11.8 psi || 201°F || 244°F || 18.0
|-
| 7,000 ft (Monument) || 11.3 psi || 199°F || 243°F || 18.4
|-
| 8,000 ft || 10.9 psi || 197°F || 242°F || 18.8
|-
| 9,000 ft (above Woodland Park) || 10.5 psi || 195°F || 241°F || 19.2
|}
Values calculated from the standard atmosphere and water's steam table; real cookers vary a degree or two.

== What to do about it ==
=== Option 1: add pressure (dial-gauge cookers) ===
If your cooker has a dial gauge and an adjustable vent, run it at about '''18 psi''' around Colorado Springs and keep sea-level times. Check your cooker's manual for its maximum safe pressure first. Have the dial gauge tested periodically; county extension offices often do this.

=== Option 2: add time (weighted cookers) ===
Most hobby cookers, including the popular Presto and All American models, use a weighted regulator that tops out at 15 psi. You cannot add pressure, so add time instead.

{| class="wikitable"
|+ Suggested times at 15 psi, roughly 5,000–7,000 ft
! Item !! Common sea-level time !! Suggested here
|-
| Agar (up to 1 L) || 30 min || 45–60 min
|-
| Liquid culture jars || 30 min || 45–60 min
|-
| Quart jars of grain || 90 min || 120–150 min
|-
| 3–5 lb grain bags || 2.5 hr || 3–3.5 hr
|}

The doubling rule is the conservative end; sea-level times already include some safety margin, which is why many local growers get away with less. If you're seeing [[Reference/Contamination#Bacteria|bacterial contamination]] in grain, longer cook times are the first thing to try.

Time starts when the weight begins to jiggle or rock steadily, not when you turn on the burner.

=== Overcooking ===
Longer cooks darken sugars. Liquid culture and agar can turn amber and caramelize if cooked much past what they need; see the notes on [[Reference/LiquidCulture/Recipes/ClemGrows|ClemGrows LC]]. Grain is far more forgiving.

== Pasteurization is different ==
Bulk substrates are pasteurized, not sterilized, at about 150–170°F. Water boiling at 201°F is still well above that, so pasteurization techniques like the [[Tutorials/Substrate/Coir and CVG|bucket tek]] work fine at altitude without adjustment.

== Sources ==
* NMSU Cooperative Extension, [https://losalamos-extension.nmsu.edu/documents/pressure-canning-at-high-altitudes-2.pdf Pressure Canning at High Altitudes]: dial-gauge pressure increases by altitude, and why weighted gauges stay at 15 lb above 1,000 ft
* Temperatures computed from the U.S. Standard Atmosphere and the Antoine equation for water

{{Cultivation}}
[[Category:Reference]]
[[Category:Basics]]

Reference/Pressure Cooking at Altitude - Revision history

imported>Claude: Batch 2: spores, cloning, culture storage, smash tek, drying, local suppliers; convert sources to footnotes

imported>Claude: Wiki rebuild: cleanup and new cultivation articles