Storing muriatic acid in the garage = RUST

jmcdtucson

LifeTime Supporter
Jun 12, 2014
344
Tucson, AZ
Recently I bought some muriatic acid sold from the pool store. It was of course factory sealed and I assumed sealed especially well given its contents, and I stored it in a cupboard on its side since it fit well that way. :brickwall:
It leaked. Ok, I cleaned up the area and removed the now dissolved shelf and vowed not to store muriatic acid in any way except upright from now on.

A few weeks later I start noticing all my tools are rusted. I thought it was due to a succession of hurricanes giving us unusually wet weather. Then, when cleaning out my garage I noticed a bike wheel had the spokes clear rusted through and that rust seemed to be worst near the muriatic acid.

Then I got online and found this is a common problem and that even sealed and properly stored muriatic acid containers have been known to leak fumes and oxidize (rust!) everything in your garage. Luckily my damage wasn't too extensive, but I could see some very expensive repairs (cars?) due to this. I guess I could go to the pool store since it's their lousy product, but I doubt it would be worth the money -seems such a dangerous chemical should be well sealed.

I'm posting this as a cautionary tale. This is a topic I've never seen mentioned on troublefreepool.com and it never occurred to me this could happen. Maybe this could merit its own article in pool school.

I'm now storing my muriatic acid in a sealed plastic box outdoors.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,256
Tucson, AZ
This is most certainly mentioned on the forum in multiple threads. And the recommendation is to always store the muriatic acid outside, often in a plastic container.

Might be worth adding a blurb in the Recommended Pool Chemicals article ....
 

jmcdtucson

LifeTime Supporter
Jun 12, 2014
344
Tucson, AZ
To be clear, I am in no way blaming any one at troublefreepools. This site is a godsend and is in no way obligated in any way to keep ignorant people like me from doing stupid things. My wife would tell you that isn't possible anyway.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,256
Tucson, AZ
:lol: You are likely correctly that an article on storage of chemicals might be a good addition.
 

Pool Tool

Well-known member
May 15, 2014
757
Western Chicago Area, IL
Most plastic bottles are designed to "vent" to prevent a buildup of fumes then subsequent bottle failure and explosion. I don't remember the MA specifically, but I know the chlorine bottle caps are marked as a "vented cap store upright" due to this. Although MA leaking in a garage is definitely a problem, a pressurized plastic bottle failing and spraying MA everywhere could be much worse.
 

timerguy

Well-known member
Oct 26, 2013
1,141
Chapin, SC
I've had 2 gals of muriatic acid (unused/unopened) in my garage for two years. Have had no leakage or any noticeable effects whatsoever. I'm assuming they're sealed at the mouth of the bottle-- the same as my bleach that I'm storing. If I opened the bottles, I guess I'd move them outside.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
Both bleach and Muriatic Acid have vented caps. So whether anything leaks from them depends on whether there is pressure buildup usually from temperature variation though with bleach the degradation can produce gas that increases pressure. Now if the bottles were sealed at the mouth so that when you first use them you have to break that seal, then that would be different -- the chlorinating liquid and acid that I get are not sealed in that way so it probably depends on the brand. The bottles are reused so the pool store just recaps them but doesn't re-seal them.
 

zethacat

LifeTime Supporter
Does MA deteriorate in strength if stored outside? I've been keeping mine on a wire shelf above my washer/dryer in the laundry room. I've only ever had 2 bottles of it since my pool is brand new but I'm guessing I should not be doing this? :confused:
 

JayBauman

LifeTime Supporter
Sep 5, 2014
617
Katy, TX
Both bleach and Muriatic Acid have vented caps. So whether anything leaks from them depends on whether there is pressure buildup usually from temperature variation though with bleach the degradation can produce gas that increases pressure. Now if the bottles were sealed at the mouth so that when you first use them you have to break that seal, then that would be different -- the chlorinating liquid and acid that I get are not sealed in that way so it probably depends on the brand. The bottles are reused so the pool store just recaps them but doesn't re-seal them.
Does California have different requirements than Texas? When I purchase gallon jugs of MA, there is a clear plastic layer under the cap that I have to puncture/remove before I can pour any out. The jug does not appear to be vented in any way. I used to store my acid in a shed with my lawn equipment. One day, I noticed a nice oxidation layer on my lawnmower, chainsaw, etc. that I attributed to venting from a 1/2 full jug of MA. I now keep the acid away from anything important.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
It may be whether the jugs are reusable or not. Buying them new probably has them sealed. Buying them in reusable jugs does not, at least where I get mine at my local pool store.

Of course that means that once you've opened the jug you may be in the situation of outgassing if there is pressure buildup from hotter temperature and if the cap has pressure-release venting.
 

jrs_diesel

Well-known member
Aug 26, 2014
215
League City, TX
I have found that I can keep a one gallon jug plus the measuring cup in a clean 5 gallon bucket with a lid. I keep mine outside on the side of my house. Haven't had any problems doing that so far.

I only buy a gallon at a time and they come sealed. My pool store carries the re-useable jugs as well in a 4 gallon tote, similar to the re-useable bottles of 12.5% chlorine (both made by HASA I believe), and those do not have the seal.