Vinegar to Lower pH

[elenaran]

This is purely hypothetical, not something I would actually try, but could distilled vinegar actually be used to lower pH? If so, what other side effects would it have?Would it effect any other readings (TA, etc)?

Again, not something I'm actually considering - just an idle thought.

 

[chem geek]

Household vinegar is fairly diluted at only 8%. It's acetic acid which is a weak acid, but with a pKa of 4.76 that's low enough below pool pH that it behaves much like a strong acid in terms of lowering the pH, but of course takes a lot more volume of it to move the pH since it's so diluted -- because of molecular weight differences, Muriatic Acid which is 31.45% Hydrochloric Acid is (31.45 * 60.05) / (8 * 36.46094) = 6.5 times more concentrated on a molar basis than household vinegar. Unlike Muriatic Acid that just leaves chloride ion leftover, Vinegar leaves acetate ion so an organic molecule. Though it doesn't react readily with chlorine, we generally don't add extra chemicals to the water that aren't needed.

[EDIT] In addition to lowering the pH, it would lower the TA in the same way as Muriatic Acid since the pKa is so low. Technically, it increases TA if you add enough of it though I'm not sure it would be that measurable -- the TA test measures chemicals that accept a proton down to a ph of around 4.5 so the acetate ion may be at least partially measured as TA. [END-EDIT]

 

[257WbyMag]

Probably wouldn't make the pool smell all that good either.

 

[elenaran]

Would it do anything to CH?

 

[chem geek]

No. CH is Calcium Hardness and acetic acid has no calcium. It's just a simple organic acid.

 

[elenaran]

Yeah, I knew it wouldn't *raise* it, but I wonder if it would lower CH. I'm just thinking of how you can use it to remove scaling

 

[linen]

If what you are getting at is removing scale then this is the proper process: http://www.troublefreepool.com/ascorbic-treatment-to-rid-pool-of-metal-stains-t2298.html. Post a full set of test results and we can help.

 

[elenaran]

No no, this is all just idle speculation - I don't even own a pool (yet)

I'm thinking if you can use vinegar to remove limescale off of kitchen items, would it "remove" calcium from the water (ie lower CH)?

 

[linen]

Well, then the answer which has already been stated...is it is better to use Muriatic Acid since the acetic acid will leave acetate where the MA will only leave salt (starts as chloride ion and often finds Na to form salt). Also MA will be much cheaper(you will use a lot less 31.45% MA then 8% Acetic). Vinegar is not a bad choice for cleaning swg cells however...

 

[chem geek]

As was noted, it's the acidity that removes calcium carbonate scale, not the specifics of the acid itself.

 

[elenaran]

what's that acetate ion do? just hang out?

 

[chem geek]

Pretty much yes, though it will very slowly react with chlorine to form some chloroacetic acids and these haloacetic acids are regulated disinfection by-products in drinking water since they are potentially carcinogenic. Again, we generally recommend against adding anything to the pool that is not needed.

 

[elenaran]

good to know!