# [Wet Thumb Forum]-White vinegar to lower pH?



## Cody (Jun 26, 2004)

Diana Walstad states that she uses plain white vinegar to lower pH. Has anyone ever tried this?
She says it's very effective and will convert to CO2 over time.


----------



## Cody (Jun 26, 2004)

Diana Walstad states that she uses plain white vinegar to lower pH. Has anyone ever tried this?
She says it's very effective and will convert to CO2 over time.


----------



## Roger Miller (Jun 19, 2004)

I haven't used it, and I wouldn't use it. There's at least one detrimental side effect to using vinegar (acetic acid) and there are several alternatives.

I have to ask, what is your pH, why is it higher than you want and why do you want it lower?

Acetic acid is excellent bacteria food. Bacteria in your tank and filter will convert it to some form of inorganic carbon. When that happens the bacteria will use oxygen and increase the oxygen demand on the tank. At the same time the acidifying effect from the vinegar will go away. If the bacteria work fast then the problems will be noticable. Otherwise all you see is that the vinegar effect disappears.

I'm not sure that the bacteria will produce just CO2. The acetic acid in the vinegar contains a negative electrical charge, so to preserve the charge balance I expect that the bacteria will produce one mole of CO2 and one mole of HCO3- (bicarbonate) from each mole of acetic acid in the vinegar. In that case, the CO2 will be used or escape, leaving you with the bicarb. Bicarb is KH; producing bicarb increases KH and that causes the pH to be higher than it was to start with. So you might get a short-term decline in pH but a long term increase in pH.

If you do add acetic acid then you will not be able to measure CO2. Acetic acid is a non-carbonate buffer and will change the readings from CO2 kits and from the KH/pH method.

If you want to lower pH in a planted tank then the first course is to increase the CO2. If you have as much CO2 in the tank as you want or can get, then you look to other ways of getting the pH down.

If you don't want to add CO2 then the best way to lower pH is to add water -- distilled, deionized water. If you mix your water with an equal volume of distilled water then (all else being the same) you will knock 0.3 off the pH. Larger proportions of distilled water will give you bigger changes in pH.

If CO2 and dilution don't do it for you, then the last way to lower pH is to lower KH by adding a strong acid. Hydrochloric (muriatic) acid or sulfuric acid are the most likely choices. Either one must be handled with care. 


Roger Miller


----------



## Cody (Jun 26, 2004)

Hi Roger,

I personally don't have a problem with the pH of my water. Immediately from the tap it's 7.0; increases to 8.0 after outgassing. Same pH as the both the stores I buy fish from and my fish are all doing great at that level.

However, it seems that a lot of people are concerned about their pH due to the number of posts on the subject but, I had never read about anyone using acetic acid and I was curious as to why.

Your knowledge on the subject is very much appreciated, but your view differs from Diana Walstad's. (Not that she is necessarily the ultimate authority on the subject, but she does write an interesting book.)

I reread her statement and she does say that on the rare occasion when she needs to decrease pH, she uses vinegar which eventually decomposes into CO2. (page 184, The Ecology of the Planted Aquarium)

Thank you for the great response!


----------



## Rex Grigg (Jan 22, 2004)

Many people read a book and see that some fish prefers a certain pH or some plant does the same. Then they think they need to achieve perfection in the tank by getting to that pH. For the most part unless your tap water comes out of the faucet in chunks you are fine.

Moderator










American by birth, Marine by the grace of God! This post spell checked with IESpell available at http://www.iespell.com

See my Profile for tank details.


----------

