Can I store wet citric acid

[vanguard]

We always have a return nozzle, powerhead, etc. to clean. I'd like to store my citric acid solution so that I could use it again.

Will it lose it citric acidy superpowers over time? Does it last for days, weeks, or months?

 

[Wasabiroot]

It should keep its concentration if it's sealed appropriately. In fact, there happens to be a paper freely available studying how the molar concentration in citric acid changes in long term storage (it doesn't)

https://pubmed.ncbi.nlm.nih.gov/6955501/

 

[elysics]

If you've already cleaned something with it, it tends to grow mold after a while. So I wouldn't, it's cheap. Or get amidosulfonic acid (certain espresso machine cleaners) you use much less of it for the same effect

 

[GARRIGA]

I have in the garage in some hidden corner citric acid I constituted some 15 years ago. Also have the powder. Now I'm curious if it is still potent :thinking-face:

 

[TangerineSpeedo]

I make up a 5g bucket of it at a time, I use it until it starts to get nasty.

 

[Randy Holmes-Farley Verified Community Expert]

it doesn’t lose potency in any reasonable time frame, but I agree that if it is no longer acidic, bacteria will grow in it.

 

[Gtinnel]

I can say from experience if left open it gets nasty and moldy within a few days. Well it did for me at least.

 

[MnFish1]

If you've already cleaned something with it, it tends to grow mold after a while. So I wouldn't, it's cheap. Or get amidosulfonic acid (certain espresso machine cleaners) you use much less of it for the same effect

Just a quick comment - there is a fair bit of debate as to how strong an acid to use when cleaning pumps, etc - especially with gaskets, etc. Some even debate the use of citric acid vs vinegar (acetic acid). The chemical may be somewhat more corrosive. However,you're correct that it's fairly widely used. Do you happen to have a protocol you could share with others (ie. use xxx concentration for yyy minutes every zzz months?

 

[Bohemian Waxwing]

Just a quick comment - there is a fair bit of debate as to how strong an acid to use when cleaning pumps, etc - especially with gaskets, etc. Some even debate the use of citric acid vs vinegar (acetic acid). The chemical may be somewhat more corrosive. However,you're correct that it's fairly widely used. Do you happen to have a protocol you could share with others (ie. use xxx concentration for yyy minutes every zzz months?

My understanding was that we use citric because vinegar degrades seals. Do I have it backwards?

 

[elysics]

Just a quick comment - there is a fair bit of debate as to how strong an acid to use when cleaning pumps, etc - especially with gaskets, etc. Some even debate the use of citric acid vs vinegar (acetic acid). The chemical may be somewhat more corrosive. However,you're correct that it's fairly widely used. Do you happen to have a protocol you could share with others (ie. use xxx concentration for yyy minutes every zzz months?

I would defer to the manual for the fauna marin one, they have it neatly packaged with possibly some hidden additional ingredients and say 10g in 500ml for up to 24 hours

I usually do these things by eye after measuring the first time

 

[MnFish1]

My understanding was that we use citric because vinegar degrades seals. Do I have it backwards?

I have not seen a difference - it depends on the concentrations of both the vinegar and the citric acid. I know some people have had issues with seals when using undiluted vinegar. You're right - some people favor citrate for that reason. I'm not sure it makes complete sense. "For example, citric acid (C6H8O7) and acetic acid (HC2H3O2) are both weak acids. Ka = 7.410-4 for citric acid and Ka = 1.810-5 for acetic acid. The Ka of acetic acid is less than that of citric acid, which tells us the following: Citric acid is the stronger acid of the two"

 

[Bohemian Waxwing]

I have not seen a difference - it depends on the concentrations of both the vinegar and the citric acid. I know some people have had issues with seals when using undiluted vinegar. You're right - some people favor citrate for that reason. I'm not sure it makes complete sense. "For example, citric acid (C6H8O7) and acetic acid (HC2H3O2) are both weak acids. Ka = 7.410-4 for citric acid and Ka = 1.810-5 for acetic acid. The Ka of acetic acid is less than that of citric acid, which tells us the following: Citric acid is the stronger acid of the two"

Interesting. For concentration, I've always followed the recommendation in this post: Randy

No dissolving seals that I know of yet.

 

[Randy Holmes-Farley Verified Community Expert]

I have not seen a difference - it depends on the concentrations of both the vinegar and the citric acid. I know some people have had issues with seals when using undiluted vinegar. You're right - some people favor citrate for that reason. I'm not sure it makes complete sense. "For example, citric acid (C6H8O7) and acetic acid (HC2H3O2) are both weak acids. Ka = 7.410-4 for citric acid and Ka = 1.810-5 for acetic acid. The Ka of acetic acid is less than that of citric acid, which tells us the following: Citric acid is the stronger acid of the two"

I do not believe the acid strength matters for this degradation concern. It is the fact that acetic acid is able to penetrate plastic to an extent, while acids such as HCl (H+ only), and potentially citric acid (much more polar than acetic acid), cannot.

 

[Joe's Coral Reef]

Does heat change the way citric acid works or something? I've noticed if I use hot water it seems to clean way faster.

 

[MnFish1]

I do not believe the acid strength matters for this degradation concern. It is the fact that acetic acid is able to penetrate plastic to an extent, while acids such as HCl (H+ only), and potentially citric acid (much more polar than acetic acid), cannot.

Thanks - do you think that the difference between an hour in citric vs an hour in acetic acid is 'clinically' significant? It would seem that concentration has to play a role? Citric acid is fairly well known to corrode/stiffen/crack rubber materials.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks - do you think that the difference between an hour in citric vs an hour in acetic acid is 'clinically' significant? It would seem that concentration has to play a role? Citric acid is fairly well known to corrode/stiffen/crack rubber materials.

The pH plays a big role plays a big role in how fast calcium carbonate is removed. Vinegar is way slower than 1 M HCl.

But the penetration of plastic is not so much a pH issue, but the nature of the acid present. one way to gauge this is by log P, the octanol/water partition coefficient. Acetic acid (log P = -0.28) is more than 10x more likely to be the the octanol phase than water, compared to citric acid (log P = -1.68) although both prefer water.

That said, I never noticed an issue with vinegar myself, and have never used citric acid for anything.