Video Summary
Sterility is critical in mycology; laminar flow hoods create a clean workspace and reduce contamination vs. still-air boxes.
Use a 2x2 ft HEPA (5–6 in thick, ≥99.97% @ 3 microns) for an accessible, useful working area without oversized cost.
Match the fan to the filter: aim for ~100 ft/min at the filter face and account for pressure drop through pre- and HEPA filters.
Choose a fan with enough static pressure (example: AC Infinity Cloudline S10, 121 CFM, ~4.25 in H2O) to overcome filter resistance.
Build the box airtight (¾ in sanded plywood, furring strips), seal with silicone, and paint gloss for easy cleaning and moisture resistance." , "Calibrate with an anemometer or simple flame test (45° tilt at ~6 in) —
Laminar flow hoods produce a steady stream of clean air that greatly reduces contamination risk and are easier to use for larger items (fruiting blocks, monotubs) compared with still air boxes, which become tedious and less effective as projects scale.
The creator recommends a 2x2 ft HEPA filter about 5–6 inches thick with at least 99.97% efficiency down to 3 microns to balance filtration and laminar flow for typical mycology tasks.
Calculate required face velocity (~100 ft/min) and total pressure drop (HEPA + pre-filter + box). Choose a fan rated to deliver sufficient CFM at the estimated static pressure—example fan used has ~121 CFM and ~4.25 in H2O static pressure.
Use an anemometer to set the filter face velocity to ~100 ft/min. If you don't have one, the video demonstrates a flame test: hold a lighter ~6 inches from the filter and adjust fan speed until the flame tilts about 45°.
Build an airtight box from 3/4 in sanded plywood, reinforce with 1x2 furring strips, seal seams with silicone, and apply gloss paint for an easy-to-clean, water-resistant surface that resists mold.
"One of the biggest challenges in mycology is maintaining a sterile working environment, which is essential to eliminate contamination that could outcompete your mushroom mycelium."
Maintaining sterility is crucial in mycology as contamination can hinder mushroom growth.
Beginners often start with a still air box, a cost-effective solution, but it can become tedious and ineffective when handling larger items and tasks.
Laminar flow hoods provide a more efficient sterile workspace that significantly reduces contamination risks when used correctly.
"In this video, I'll explain how to design a flow hood from the ground up, including component selection and other considerations, as well as giving you an overview of the build process."
The speaker aims to construct a high-quality flow hood that ensures optimal performance, despite the $600 cost being higher than budget options.
A basic understanding of materials and components is necessary to build a functional flow hood.
The HEPA filter is the heart of the flow hood, and a 2-foot by 2-foot filter is chosen for this project to balance size and effectiveness.
"To ensure the flow hood operates correctly, you need to ensure that the HEPA filter and fan are compatible, and that the air coming out of the filter is moving at 100 feet per minute to achieve laminar flow."
The compatibility of the HEPA filter and the fan is essential for achieving laminar flow.
An efficient HEPA filter should be at least 5 to 6 inches thick and have a filtration efficiency of 99.97% at 3 microns.
It is also important to consider the pressure drop created by the air passing through the filter and pre-filter when selecting a fan capable of maintaining adequate airflow.
"Most inline fans that I looked at didn't come with a fan curve, so I had to deduce whether they would work based on their maximum CFM and static pressure."
The fan's capability to handle air pressure and produce sufficient airflow is critical for the hood's effectiveness.
The speaker emphasizes evaluating fan specifications, such as maximum CFM and static pressure, to ensure the fan can meet the required airflow of 400 cubic feet per minute.
The chosen inline fan, with a maximum airflow of 121 CFM and a static pressure of 4.25 inches of water, surpasses the requirements, ensuring robust performance for the laminar flow hood.
"The pressure of a flow tends to increase over time as particles collect in the HEPA filter, and you may need to increase the speed setting on the fan."
"I settled on ¾ inch sanded plywood for my box because it's easy to construct into an airtight structure and thick enough to absorb the vibrations of the fan."
"Purchasing a hole that fits the diameter of your fan is hugely helpful for making the hole for it to sit in."
"Painting the hood is not just for aesthetic purposes; gloss paint is much easier to clean than raw wood and provides a water-resistant barrier."
"If you have an anemometer, you can easily use it to find the fan setting that gives you 100 ft per minute of flow."
"The dish that wasn't in front of the hood developed lots of bacteria and mold within a week, but there are still no signs of contamination in the dish that was in front of the hood."
