Q: Proper pH-down solution for rockwool?

[K N and P J Harris]

> ==========
> bionet/plants #2256, from ksands at users.jaxnet.com, 1050 chars, 20 Sep 
1996 20:29:55 
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> Article: 10805 of bionet.plants
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> From: ksands at users.jaxnet.com (ksands)
> Newsgroups: bionet.plants
> Subject: Q: Proper pH-down solution for rockwool?
> Date: 20 Sep 1996 20:29:55 GMT
> Organization: Southeast Network Services, Inc.
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> What are some of the best and/or easily available solutions or
> chemicals to use to adjust the pH lower in your hydro nutrient
> mix?  I've heard:
>  
> A) Vinegar is unreliable as it will evaporate
> B) Some sort of powdered vitamin C that should be available at
>    healthfood stores will work. (Scorbic acid is it?)
>  
> If neither are good, please list some alternates, where they
> might be purchased (locally preferred), and what sort of ratio
> with water that they should be mixed to.
>  
> Thanks!
>  
> ksands at jaxnet.com
> 
Both vinegar and ascorbic acid are organic acids and will readily 
degrade thus losing your pH control (vinegar = acetic acid will degrade 
VERY quickly). The best bet would be battery acid (sulphuric acid) but 
if this seems a bit "non-organic" why not try the major gift of the USA 
to the world - Cola. This is quite strong phosphoric acid (and a good 
buffer to boot) and if it's OK to foist it on the world - why should a 
few plants object ?
Peter Harris, Reading, UK.