I looked for some advice on this but was struck that lots of the advice given was by people or companies that have no basic (Ouch chemistry of acids related pun) knowledge of chemistry.
OK this isn't going to be half a page showing how much I know but be of no use to you it's going to be the shortest explanation of the reason why dosage isn't important in the way you might think it is.
This is because it's getting on for 35 years since I did any chemistry and I'm embarrassed about how little I remember.
Not only are there different types of acid e.g Sulphuric, Nitric, Citric, Acetic etc but some of these acids behave in different ways. (BTW My former chemistry teacher would stress that Acetic Acid is properly named Ethanoic Acid but then again as I'm going to be referring to Citric Acid and not 2-hydroxypropane-1,2,3-tricarboxylic acid we shall not bother using proper names.)
Acids are substances that break up in solution, they dissociate (dissociation is the important term here) they dissociate into Ions. Now what an ion is is beyond the scope of this but what is important is the dissociation. Generally:
Mineral Acids that is Sulphuric, Hydrochloric Nitric etc dissociate completely. i.e. the more of the substance you add to water the stronger the solution gets. e.g The strength of sulphuric acid in a
battery would need washing off your skin soon after spilling it upon your skin whereas a high strength solution would cause instantaneous burns.
Organic Acids tend to have limited dissociation (Though the number for the dissociation constant is higher than a strong acid) They dissociate till a certain level of acidity then stop dissociating further. If you add
too much acid the solution will be no stronger than if acid was added to the limit of dissociation.
What I don't know? What value of citric acid to add to reach the dissociation limit. I have a figure for the limit of solubility of 59g/100ml at 20[SUP]0[/SUP]C but think the limit of dissociation may well be at a lower point.
What will affect dissociation and so speed or retard the process? Temperature affects the dissociation there will be greater dissociation at a higher temperature. So a boiled heater will process faster than a room temp one.
So ho much to add? Alas my answer comes from this for kettles which I think will work out at about 40g/litre and is meant as a fast acting descale. Alas I don't know if they plucked the figure out of the air or if it has any consideration.
http://www.morphyrichards.co.uk/Pdf/IB43772.pdf
My big point is to not worry about adding too much citric acid.
Thing someone might like to try. Using this suggestion from
kettle descaling - citric acid? - MoneySavingExpert.com Forums
Believe it or not I use lemonade - put it in the kettle, boil and leave over night rinse out a few times in the morning, boil again pour out and rinse again - did mine today it worked!
I use the cheapest supermarket one at 17p it 's a bargain
Sourcing the cheapest form of citric acid at 17p-20p for 2 litres.
Thing you might not want to try. Asking for citric acid at your local pharmacy. I'm afraid that many of their "regular customers" (When were you first in a queue in a pharmacy and spotted some customers get served straight away?) will know only two well that citric acid aids in dissolving brown heroin.
If interested see:
Organic acid - Wikipedia, the free encyclopedia
Acid dissociation constant - Wikipedia, the free encyclopedia
Acid
