Muriatic Acid vs Dry Acid

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
5,529
San Clemente, CA
Muriatic acid is much preferred. The major downside is the fumes, but with precaution should never become an issue.

Dry acid (sulfuric) adds sulfates to the water which can become very problematic with time. It is also typically more expensive. Sulfuric acid is usually marketed as a safer alternative (no fumes) but possess much greater risk if it comes in contact with the body.
 

Texas Splash

Mod Squad
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Jun 22, 2014
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I'm with Brian. I started with dry acid in my early days when I visited the pool store a lot, but now that I'm on my own with TFP it's MA for me. Much simpler. :goodjob:
 

C3Cl3N3O3

Bronze Supporter
May 25, 2015
324
Fort Mill, SC
So do sulfates cause any issues on vinyl pools? It seems like it's all about issues with grout in the threads I've found. The dry acid isn't THAT expensive, so I'd prefer to stay with it if I can.
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
5,529
San Clemente, CA
I don't know of many issues in vinyl pools unless you end up getting scale (which would take high calcium levels and very high sulfate levels) to become problematic. Sulfates are a very bad thing for SWG pools as well. Do you have concrete decking around the pool?

My knowledge is limited though...
 

JoyfulNoise

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May 23, 2015
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So do sulfates cause any issues on vinyl pools? It seems like it's all about issues with grout in the threads I've found. The dry acid isn't THAT expensive, so I'd prefer to stay with it if I can.

Dry acid is sodium bisulfate. After dissociation of the acid salt, it leaves behind the sulfate ion. Sulfates can damage concrete & plaster as well as degrade the coatings on SWG plates. At high enough concentrations, sulfates can react with calcium to form spindly, needle-like crystals of calcium sulfate (gypsum). Sulfates can only be removed by draining water. While its use in vinyl pools is typically not as problematic as in plaster pools, scaling of gypsum crystals can increase the risk of liner puncture.

You can certainly use dry acid if you wish, but you are adding something to your water that your pool does not need.
 

Deb04

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Jul 12, 2008
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I use Dry Acid, despite the recommendations against with my SWG because I used MA once and was overwhelmed with fumes. I live in a very windy area of the country, the air is seldom still, and the wind only stays in one direction if there is a storm. Otherwise it changes direction every couple of seconds. Trying to get downwind of the stuff was almost impossible. My SWG is on it's 9th season with no issues.

That being said, I use acid seldom, maybe once or twice a year. But I have a problem with pH drifting low, not high, I believe because my fill well water is <7. If I had to use it as often as others do, I might get a mask and deal with the MA.
 

Saturn94

Bronze Supporter
Mar 11, 2015
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First person I've ever heard of with a SWG that doesn't get pH rise. Lucky you.


My pH stays at 7.4/7.5 all season even with the SWCG. I haven't had to add acid in years since tweaking my TA and adding borates. :)
 
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Ncdamsel

Well-known member
Jul 3, 2015
66
Garner ,NC
i like to use the Muriatic acid i used dry last year the Muriatic acid made me nervous but since my boy friend is doing that part(this year for me) i use the Muriatic acid now its seems cheaper and seems to work better in my opinion
 

jmastron

LifeTime Supporter
Jul 21, 2014
325
Sacramento, CA
I use Dry Acid, despite the recommendations against with my SWG because I used MA once and was overwhelmed with fumes. I live in a very windy area of the country, the air is seldom still, and the wind only stays in one direction if there is a storm. Otherwise it changes direction every couple of seconds. Trying to get downwind of the stuff was almost impossible. My SWG is on it's 9th season with no issues.

That being said, I use acid seldom, maybe once or twice a year. But I have a problem with pH drifting low, not high, I believe because my fill well water is <7. If I had to use it as often as others do, I might get a mask and deal with the MA.

Be careful with a mask -- there was one person here who put on a full respirator, and ended up with an eye injury that required time and ophthalmologist care to heal; clearly exposed to a lot more fumes than they otherwise would have tolerated.. Honestly I think it's better to not use a mask and to back away as soon as you smell any fumes. I do wear goggles to protect against splashes (but not gloves, because my understanding is that getting it on your skin isn't a major issue if you rinse it off ASAP)

A good tip is to never pour into a measuring cup; open the jug, float it in the pool, and pour right into the water. I mark my jugs with 1/4, 1/2, and 3/4 lines from a stick I calibrated once with water, then use that to control how much I put in. It doesn't usually have to be exact.

You can also get lower strength MA -- around here Home Depot sells both 31% and 14% MA in similar 2-gallon boxes; the 31% is $1 more so obviously the better value, but if I had to deal with wind when pouring I'd gladly pay a bit extra for the lower strength; I accidentally bought it once and it does fume a lot less.

While dealing with liquids has issues, as mentioned dry chemicals can have similar issues (e.g. when you open the bucket of dry acid) or worse.
 

needsajet

TFP Expert
LifeTime Supporter
Jan 4, 2016
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+1 to safety glasses for working with muriatic acid, and +1 to muriatic acid for the pool.

Getting comfortable with MA by using the weaker percentage for a while is a good idea.

My better half gets a half full pail of pool water first, then adds the acid into that water. This kills the fumes right away. Water from the garden tap would be fine as well. Then she takes the pail to the pool for pouring it in.
 

wjr75

LifeTime Supporter
Jun 6, 2013
896
IL
I use muriatic acid and wear sunglasses and hold my breath when I pour than walk away and breathe :pirat:.
 

jmastron

LifeTime Supporter
Jul 21, 2014
325
Sacramento, CA
+1 to safety glasses for working with muriatic acid, and +1 to muriatic acid for the pool.

Getting comfortable with MA by using the weaker percentage for a while is a good idea.

My better half gets a half full pail of pool water first, then adds the acid into that water. This kills the fumes right away. Water from the garden tap would be fine as well. Then she takes the pail to the pool for pouring it in.

I may be overly paranoid, but I get nervous when I hear people say this, maybe because I'm picturing someone dragging a huge pail of sloshing water+MA (diluted but still very acidic) across the pool deck; seems to invite a lot of changes to spill on clothes, the deck, etc. To me, getting into a stable position at the edge of the pool, opening the MA jug, and pouring it from an inch above the water seems much safer. In the pool, you can put the jug itself partly in the water so the spout is very close to the surface, which you can't really do when pouring into a narrow bucket. I got that technique from people here, after initially doing the pour-into-a-measuring-cup thing until I saw one night by flashlight just how much fume came from doing that.
 
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YippeeSkippy

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Just as a general warning for folks who may want to do it this way- remember to always pour the MA *into* the water, not the water into the MA.
 

needsajet

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My wife's a bright gal and plenty strong enough to lift a half-full pail! She's a 20-year pool gal with a fondness for clothing I'm yet to entirely comprehend, but I've never even thought about her choice of pail ;)

No sloshing buckets allowed, unless they're filled with ice and coldies!
 
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