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Hey all,

I want to give yeast washing a shot with chlorine dioxide. My plan with the conical is to save yeast slurry between batches in mason jars but I'll be revolving through some different yeast strains so I may not reuse right away.

For those who've done this, where did you get your chlorine dioxide? Water purification tablets from MEC or something?

I'll keep on with my research but,

What concentration do you use?

What's your process?

Thanks!
-Rob

You should have asked this question at 3pm....

When you had access to chlorine dioxide, or were sober?!

I'm in no rush for it, thanks. Yeah my next course of action is to scour probrewer.

Here's a document on ClO2 I found.

That's right.

That's the document that started it all for me. I called the author with questions and he was very helpful.

Anywho, you've got the target PPMs to shoot for. Just remember to calculate for the total amount of slurry you're washing @ 20 - 50 ppm. I generally always shoot for 40ppm.

Ok, here goes.

I picked up a liquid based water purification kit from MEC containing stabilised Chlorine Dioxide (2%) and food grade Phosphoric Acid (5%). The ClO2 needs to be activated with the acid to be released. The instructions say to mix equal parts of the two, let react for 5 minutes, then add to a volume of water. The activated ClO2 has a limited half life and will degrade over time (that's why they make you activate it).

Link to kit:
http://www.mec.ca/product/4013-495/pris ... treatment/" onclick="window.open(this.href);return false;

Here's a nice ppm (Parts Per Million) dilution calculator:
http://www.physiologyweb.com/calculator ... t_pph.html" onclick="window.open(this.href);return false;

Acording to the "Yeast Washing With ClO2" doc posted earlier I should use (up to) about 50 ppm. This goes along with what Nash said and the consensus over at Pro Brewer. Some people use higher concentrations but I wouldn't use too high a concentration with extended contact time.

I had a potentially nice and dirty starter so I aimed for about 55 ppm concentration of ClO2 before I pitched the yeast. My starter was 1500 ml. I decided that it would be easiest to use this purification kit in two steps, 1) make a small 250 ml solution of specific concentration 2) combine that with the starter for a total volume of 1750 ml.

I did the calculations in reverse. I figured out what ppm of 250 ml ClO2 solution that I'd need to add to my 1500 ml starter to have about 55 ppm ClO2 in the total 1750 ml. The calculator told me I'd need to have a 380 ppm in 250 ml solution. I then calculated how much of the kit I'd need to make 250 ml of 380 ppm ClO2.

The kit contains 2% ClO2. 2% is 20,000 ppm. Acording to the calculator I'd need 4.75 ml of that for 380 ppm in 250 ml.

I used a medicine cup and syringe I had for giving antibiotics to my daughter. If you have kids you know what I mean! Perfect tool for the job. I poured a bit of solution into a medicine cup and then sucked 4.6 ml into the syringe. I decided to round down a bit since it was easier and well within tollerence. I put that into an empty 250 ml flask, rinsed the syringe, put the excess ClO2 back into the container, rinced the cup, and repeated the process with the Phosphoric acid. I swirled the flask around to mix, waited 5 minutes as per the instructions, then topped up to 250 ml with water.

I pitched that into my 1500 ml starter, swirled around a few times, then pitched that into my brew about a half hour later.

Easy right?



Sent from the brew timer.

Good luck! Fwiw, I've gone up to 300 ppm washing yeast, but not for long-term storage.

Yeah thanks for the info, might jump on that myself with any strains I want to store a while. The mec kit seems like a straighrforward way!