Hey, I'm an environmental engineer but am working on a PhD in analytical
chemistry. I've got some ideas from my masters research that may apply to
I worked with mixed cultures (activated sludge and anaerobic digesters)
for removal of chloroorganics. Incidental to this research, I also worked
with white rot fungus--which required 90-100% humidity and constant
removal of CO2 .
The trick I came up with for humidification was to bubble my dry air
through a glass diffuser into a beaker filled with a saturated potassium
dichromate (K2Cr2O7) solution. The bubbles were slowed (to allow full
humidification) by glass wool in the solution. I pulled this out of
Lange's Handbook of Chemistry, the section on maintaining constant
humidity. At 25 C, you get 98% humidity.
The reason this was preferable for my purposes is that I had to maintain a
pristine, uncontaminated culture (sound familiar?) but I was introducing
"dirty" air (aspergillum niger was my main problem). The dichromate
solution is usually used for cleaning microbiology glassware because it is
such an incredibly strong oxidant. And, as a non-volatile (inorganic
salt) it stays in the jar.
Some caution must be taken when using this stuff. It'll soar right
through your clothing, flesh, and bones; but, you can handle it with most
lab gloves. It's also good for cleaning your glassware (terrarium or
spawn jars) prior to autoclaving, as appropriate. The stuff turns from
orange to yellow to green to blue as it is used up. Try not to flush it
down your sink--heavy metal hazardous waste that will destroy a septic
tank culture and do a great deal of damage to a publicly owned treatment
works (POTW) and probably will get traced back to the source.
Also, I don't think a bubbling stone is a good idea--use glass (go to a
college science supply store in the biology or chemistry departments and
ask for a gas dispersion tube).
This one came from using a respirometer to measure bacterial growth rates,
originally, but works well for CO2 in a fungal culture as well. A 50mL
beaker (baby food jar...) is filled half full of sodium hydroxide or
potassium hydroxide (NaOH or KOH) pellets. This is left in the growth
chamber where CO2 is scavenged as long as you can see the pellets (it will
eventually convert to an aqueous bicarbonate solution...it's still working
while the pH is higher than the pKa for bicarbonate (around 6.3 ???) but
it's cheap and available so replace it freely.
Don't get any metal into this stuff! Reaction is immediate and can be
violent and results, often, in the liberation of H2 gas.
Another problem is that the stuff will regulate the humidity local to it
(lowers to about 15% relative humidity). My strategy was to place the CO2
scrubber adjacent to the vent hole (necessary since air is constantly
pumped in; the vent was attached to a hose the other end of which was
submerged in dichromate solution to keep from contamination of the rest of
Using these 2 methods allowed me to maintain 95% humidity (+/- 3%) for 6
months, as measured continuously at the center of the chamber. As
necessary (usually when replenishing the scrubber), I topped off the
If you try it, let me know how it goes--I'm completely out of the
mycology/microbiology business now, but have been keeping up with
developments, none-the-less. I might buy some perlite soon to test its
compatibility with dichromate; I'll let you know what I find out.
Feel free to disperse this as you see fit. Any attribute (or grief)
should be given to "Bun Justice Botanicals" and inquiry can be posted to
alt.drugs.mushrooms or sent to me at firstname.lastname@example.org.
Disclaimer and warning: Any advice I give is worth the price you paid.
Methods are only proven valid for white rot fungus, a delignifying agent
valuable to the pulp and paper industry as an alternative to chlorine
bleaching. I will maintain your privacy as well as I can, but this is a
campus account and no more secure than any other campus account; I have
nothing to hide, but if YOU do then take appropriate precautions prior to
contacting me. Any and all requests for anything illegal will be deleted
and forgotten (as will any abusive or otherwise stupid correspondence).