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Author Topic: Minimizing microbial growth in circulating water baths  (Read 1573 times)

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Babcock_Hall

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Minimizing microbial growth in circulating water baths
« on: September 08, 2018, 06:18:30 AM »

I just cleaned what looked like algae out of a circulating bath made by Laura.  I am not sure how to minimize their return.  I may have used a mixture of ethylene glycol and water in the past.  This bath is high enough  up on a bench that I don't see how a dog could potentially lap up ethylene glycol (which can happen in other contexts).  Any suggestions?
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Re: Minimizing microbial growth in circulating water baths
« Reply #1 on: September 11, 2018, 12:41:52 AM »

I use a water cooler which stores water for my calorimeter. I have to flush it out quite regularly to avoid biological build up. We are supposed to add a biocidal liquid supplied by the manufacturer of the calorimeter  -  I stopped buying it as they put the price of the biocide up 10 fold. It is about £50 for a few ml now!   So, I now use some of the biocide that I use in a paint formulation to add to the water to prevent/retard fungal/biological growth in the water cooler.

I guess using biocidal liquids are a no go because of the dog? If it is kept out of his reach I suppose it could be OK. 
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Babcock_Hall

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Re: Minimizing microbial growth in circulating water baths
« Reply #2 on: September 11, 2018, 03:02:36 AM »

There should not be any dogs around, but one always worries about chance events.  I am leaning toward using some antifreeze.
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Arkcon

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Re: Minimizing microbial growth in circulating water baths
« Reply #3 on: September 11, 2018, 04:32:40 AM »

Basically, the answer is frequent draining, cleaning and drying.  There are many commercial products available, and some good ones on your own, solvents and the like.  But in the end, the inhibitor gets consumed, dust accumulates, resistant organisms grow, the water evaporates and gets topped of, overflows get drained, then with refilling, the solution gets dilute again.  And you have to drain, wash, and dry.
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Re: Minimizing microbial growth in circulating water baths
« Reply #4 on: September 11, 2018, 05:31:39 AM »

nano particulate silver or copper particles would probably work also.
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wildfyr

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Re: Minimizing microbial growth in circulating water baths
« Reply #5 on: September 11, 2018, 08:22:43 AM »

Antifreeze seems best and simplest to me. If this is a lab how could a dog get to it?

A bit a bleach works too if its all plastic.
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Babcock_Hall

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Re: Minimizing microbial growth in circulating water baths
« Reply #6 on: September 11, 2018, 08:32:44 AM »

Dogs should not get in, but sometimes the unexpected happens.  Fortunately, the bath is on a bench top; therefore, doubt that this is a serious concern.
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Re: Minimizing microbial growth in circulating water baths
« Reply #7 on: September 11, 2018, 10:19:50 PM »

A bit a bleach works too if its all plastic.

I'd thought about bleach for my water cooler, but I was unsure how it would get on in the calorimeter so I stuck with the biocide.  I guess a recalibration maybe needed due to the change in specific heat capacity of the bleach/water system compared to just water, but other than that I guess it would be fine. The difference might even be negligible idk.
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