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alcohol as a biocide?

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No, I showered
Feb 27, 2002
Nashville, TN
I read some discussion somewhere about using rubbing alcohol in a water cooling system in place of water-wetter, etc as a biocide to kill off any growth. Assuming that I'm using all copper and no Al, does anyone know what concentration I would need to use to make that work? Would there be any other side effects of it that you know of?

I've never heard of anyone using rubbing alcohol as a biocide. Not saying it can't be done, Iv'e just never seen or heard about it. Click Here to view a previous thread about biocides. Portishead works with biocides, I assume in conjunction with a municiple water supply, and had some suggestions. This thread was more about bongs, but a biocide would act the same in a closed system. Also, you might PM portishead and ask his opinion of rubbing alcohol as a biocide. I think he would be the resident biocide expert on the forum.

I assume you need a biocide because you are running an open loop system like a bong. While I imagine alcohol would make an excellent biocide, I also imagine it would evaporate a lot faster than the water it is mixed in, leaving little or none remaining after a short time. Don't you think?

If you are running a closed loop system, water wetter not only enhances the wetting action of the water, but I bet it's a pretty hostile environment for living organisms when you mix it to the recommended concentration in distilled water.

I use accu-clear in my water systems. You can get it at any fish store and its probably not bad in a bong system since its fishie safe. Phiber took my reccomendatin and it cleard up his cloudy water pretty quickly. He is using an open system so its even more important to use a biocide.

Hey pudgy-duck its nice to see your around ;)
Well, I actually will have a closed loop system. I was just wondering about the Alcohol because I don't want Water Wetter staining my hoses red as I've heard happens after a few weeks. Since I'm planning on running with a black light CC and florescent dye, I don't want red hoses interfering with that.

As far as that goes, does anyone know the heat capacity of Alcohol? I'm sure it's probably not as good as water, but has anyone ever tried running pure alcohol or a good water/alcohol mixture in their system? Any idea how it would affect cooling or conductivity?
I played around with rubbing alcohol in my bong for a day and saw a very small drop in water temp., better evaporation as Hoot said, but the smell! I could have sworn I just walked into an ER. I used about 12-13oz. to 4.5gal water. It does not have anywhere near the heat capacity of water but in a weak mixture I think it would be just as good as anti-freeze just don't do it in an open system unless you like that hospital smell.:D
Well, if I start smelling it after it's all in there, then that tells me that something's wrong cause it's leaking. But hey, at least it's not as horrible smelling as Water wetter, right?

Another interesting thing about alcohol and water mixtures. The alcohol molecules are much larger than the water molecules. So the water molecules will fit between the alcohol ones. So if you were to take, say, 10 ounces of pure water and 10 ounces of alcohol and mix them well, the resulting mixture would take up LESS than 20 ounces. Freaky huh?
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To answer the question - rubbing alcohol is 80% and in the dilution you are using it in it won't work because alcohol kills organisms to dehydrating them i.e. sucking the water out of them as alcohol has a high affinity for water. The alcohol is saturated so its not going to work.
You have discovered the other property - fractionation. In a mixture of liquids, the liquid with the lowest boiling point will always evaporate first so after a short period all the alcohol will have evaporated.
You are right about the smell. I used it as a substitute for antifreeze in an experiment to see if the viscosity of the coolant at -25C would improve. That wasn't a success and the family threatened to kick me out with the system if it wasn't removed.
Maybe you shoudl try some isopropel alcohol(spelling wrong). Better known as dry gas for cars. Not as popent as rubbing alcohol but may suit your purpose.
Rubbing alcohol IS isopropyl alcohol and is avilable at the drug store in 2 strengths usually 70% or 90%. I use the 90% for cleaning stuff like thermal grease since it evaporates faster than 70%.:)
Methanol is whats used in gas drying products like Heat.
There is an extensive thread somewhere in the forum that investigates the use of methanol/water mixtures for cooling.
Oh, HERE it is.:D
Personally I'd go for a seven & seven or a vodka tonic solution, that rubbing alcohol will make you go blind.

I don't know what I was thinking, you are right, it would be way to diluted to do any good. I should known that because of the time I spent as a firefighter/medic. Maybe it is lingering affects from the water bong! lol
A seven/seven in my water rig? It'd be handy for refilling my glass but I think I'd be running out of coolant for the system pretty fast. Why not go all out and use Everclear?:beer: