30 gallons of acid???

G

Guest

OK, just coming back in from a job where the plaster company wants to do an "in pool acid wash" and is suggesting 1 gallon acid for every 1,000 gallons of water. Pool is 30,000 gallons, so even I could do the math :lol:

Opinions?
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,406
San Dimas, CA (LA County)
Opinions, you say?

Well, my opinion is that since you're in the business, give the guy a quote for a new heater.

Sounds like overkill. Kiss the tile grout goodbye. Kiss the deck goodbye. Kiss the lawn goodbye.

Why are you involved? After they dissolve his walls, they want you to filter it out?
 

Butterfly

TFP Expert
LifeTime Supporter
May 30, 2007
10,045
South Carolina
:shock: Dunno, no opinion here. I was just thinking how much the PB added when we had our pool replastered......

Bruce, will you take pics for us - you know, before and after? :-D
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
Three or four gallons of acid for 10,000 gallons of water is what I think of as normal. They are talking at least two and a half times that much, which seems rather excessive.
 
G

Guest

Thanks for the visual of the pool walls crumbling, Richard :shock: :lol: That was good!

I am there since the TDS on this pool is 4,020 and the CH is 690. The plaster company owner referred me to the pool (I used to work for him, and he is a great guy. We work on several projects together still.) to handle the hard water conditions (it is a beautiful pool, PebbleSheen and lots of fantastic rock work and landscaping.). However, there is quite a calcium build up on the floor and bench area, and I know that my system alone cannot remove that, sot hey are considering the in pool acid wash prior to me doing my work.

Jason, the directive reads that on day 1 they will shock the pool with 1 gallon per 1,000 gallons of water and add Blue Stuff and a circ pump. They will monitor the pool until chemicals spike (?) and wait until calcium levels reach 500 (? again!). They will then brush and drain pool, pressure wash and fill. It's that volume of acid that really tripped me up and made me feel the need to post the question!

I'll take all the info you guys can provide! I see big problems personally with that quantity, and I sure would not suggest that amount. That is a lot :shock:
 

257WbyMag

TFP Expert
LifeTime Supporter
Feb 23, 2008
5,061
Denton, TX
All at once? :shock:

I love The Pool Calculator...

"Adding 3840 oz. of 31.45% muriatic acid will lower the pH by 30.74 and lower TA by 501"

Your pH can only be as low as 1 of course and the TA can only be as low as zero, but still, wow!
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,381
Pleasanton, CA
The water has to be really aggressive in order to remove the calcium but I would think that 1000:1 would still take some time to fully dissolve the calcium. I was under the impression most direct acid washes are much higher in concentration. It seems like a lot to go through when they are planning to drain anyway. Why not drain and do a direct cleaning? Not only that but this method will remove calcium everywhere and not just where it is a problem.

Also, CH will increase not decrease so I don't understand why they would be waiting for CH to go down to 500 ppm.
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
My experience with direct acid washing, several times, on very old and then ageing plaster, 12 years after the pool was replastered, leads me to these questions and comments, albeit few.

What color is the plaster and how old is it?

How extensive is the scale? Solid or spots? Of course there will be areas that are much more or less thick.

As I have colored plaster judging just how much plaster is removed, while removing scale in unevenly distributed scale areas, is much easier to see, as the dissolving plaster comes off in a dark color, unlike the runoff of the scale, even when it is stained.

The last acid wash I did on my pool was 2008. It was around the 5th acid wash I had done on the pool in 22 years; two on the old white plaster and three on the blue plaster, applied in 1996. The blue plaster heavily coated with scale in some areas and lightly coated in other area. I didn't determine this until the first wash was done using the weakest solution. I decided to not hit the bottom of the pool very hard as it was pretty well spotted with areas of thin to no scale and some areas of very, very heavy scale, for fear of dissolving too much plaster.

Of course you know about my two hours of angle grinding, using concrete disk, on just one step.

Here's what I observed after finishing, which might be of benefit. My friend and I did the last process in two full days, probably took us 20 hours, with lot of breaks. It was 100 F outside so we had to "stay alive".

We did not directly acid wash the basin of the deep end where some of the heaviest scale was laid. During the process we allowed about 2.5 to 3' of rinse water and acid to collect in the basin. I neutralized it with baking soda and pumped it out, doing this many times, over the two days. I don't know what the pH of the water became before I neutralized and pumped out as I was only using fresh test strips. From watching one video we took, after using 6 bottles of acid solution and collecting it in the basin over about two hours time, the volume of the basin was about 2.6-3 K gallons of water and 6 gallons of acid. BTW.... I had been adding baking soda every once in a while, while this acid pool was collecting so I only needed to add about four more lbs before the pump out. So pH was not "6 gallon pH the whole time". Sorry I can't be more specific. The calculation called for 2 lbs of baking soda per gallon of 3x.x MA and I had already added 8 lbs of baking soda, couple lbs at a time, during the two hours.

At any rate, after the job was finished and upon refill there was an almost scale free bowl in the deep end of pool. I'm posting a YouTube in a bit so you can see the pool (and me, and hear dear Shelsey's voice) It doesn't appear that much excess plaster was removed.

gg=alice
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
One gallon of acid added to 10,000 gallons would lower the TA by 50 ppm. So adding ten times that amount is going to wipe out the TA and lower the pH significantly to around a pH of 2. Basically, if you started with a TA of 100 ppm, the first two gallons (in 10,000 gallons) would wipe out the TA and the next 8 would be an 8:10,000 dilution of full-strength Muriatic Acid that has a pH of -1. That's roughly a factor of 1000 which is 3 pH units where -1 + 3 = 2. Jason's pool calculator isn't designed to do such extreme calculations.

The exposure time is limited so perhaps this is what is done for an acid-wash, but I wouldn't want my other pool components exposed to this for very long.
 

Grape Ape

LifeTime Supporter
Jul 12, 2009
121
Seattle, WA
chem geek said:
One gallon of acid added to 10,000 gallons would lower the TA by 50 ppm. So adding ten times that amount is going to wipe out the TA and lower the pH significantly to around a pH of 2. Basically, if you started with a TA of 100 ppm, the first two gallons (in 10,000 gallons) would wipe out the TA and the next 8 would be an 8:10,000 dilution of full-strength Muriatic Acid that has a pH of -1. That's roughly a factor of 1000 which is 3 pH units where -1 + 3 = 2. Jason's pool calculator isn't designed to do such extreme calculations.

The exposure time is limited so perhaps this is what is done for an acid-wash, but I wouldn't want my other pool components exposed to this for very long.
Bruce said they are bringing in a circ pump, so perhaps they plan to plug all the pipes first.
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
My "Favorite Most Trusted" pool guy does the filled pool acid washes. When he was putting in my pump and filter (and changing out a lot of plumbing and moving the filter location - he was here most of the afternoon, so we got a lot of pool chat in) his helper called a couple of times to verify some things for the filled pool acid wash they were in the middle of. He seemed to be really calm about it and let his guy, "in training" handle it for that day.

I can call and ask him his process if anyone wants to know. He's been in the business for over 25 years. I've know him almost that long and trust him and his service. He's a no frills sort of guy, not at all pushy, and doesn't tout knowing it all; "no brag just facts mam". Virtually all the pools, out this way, are plaster. BTW.... he doesn't do regular pool maintenance; just "upper" level services but does refer business for solar installs, etc. He likes for the experts in their fields to do what they do best while he does what he does best.

gg=alice
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
Richard320 said:
Opinions, you say?

Well, my opinion is that since you're in the business, give the guy a quote for a new heater.

Sounds like overkill. Kiss the tile grout goodbye. Kiss the deck goodbye. Kiss the lawn goodbye.

Why are you involved? After they dissolve his walls, they want you to filter it out?
Semmeh down. :whip:

All of those things can be protected by just not getting anything on them. Not all service people are slobs after all. And the acid "solution" is really easy to neutralize.

As they are "in the business" surely they will know to lower the water. They are, after all, a plaster company and not just some odd-job "joe". Even I know to do that as I know to not let any acid solution reach my pumping station or any metal parts of the pool, like rails, fixtures, metal jets or returns, etc. I even knew to remove the stainless screws in the bottom drain. And I'm "just a girl". What do girls know? :p

If the plaster company has been in business for years, surely they know what they are doing??? They have been in business for years, haven't they??

gg=alice
 
G

Guest

This is exactly the kinds of responses I was looking for! You guys (and girls!) are great (and somewhat predictable :lol: )!

The plaster company has been around for 40+ years, and I spoke to the owner this morning and he assured me that this was acceptable. They are going to do the in pool acid wash and I am going to R/O the water after they are done. Should be a great looking pool when it is done!

Just had to think 30 gallons is a lot of acid :shock: Better safe than sorry, so I thought I would ask. Thank you for all the replies so far!
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
simicrintz said:
This is exactly the kinds of responses I was looking for! You guys (and girls!) are great (and somewhat predictable :lol: )!

The plaster company has been around for 40+ years, and I spoke to the owner this morning and he assured me that this was acceptable. They are going to do the in pool acid wash and I am going to R/O the water after they are done. Should be a great looking pool when it is done!

Just had to think 30 gallons is a lot of acid :shock: Better safe than sorry, so I thought I would ask. Thank you for all the replies so far!
Great :goodjob: Isn't information marvelous? :-D

I'm still attempting to load the video clip to YouTube. What the heck... I've been wanting an excuse to share it. It is only a small part of what we recorded. The night before was when I slipped and tore my rotator cuff tendon. When Shlesey was visiting, from the west coast, DH cooked us some wonderful meals. The night before, after everyone was "well fed and bedded", I did the two hours of angle grinding on the bottom step.

I'm for hire for air fare, drinks and good food and company. :mrgreen:

gg=alice
 
G

Guest

Just to clarify my earlier post where I said some of you were predictable ( :oops: ): What I meant, even if it did not come across that way, was that I had hoped (expected) responses from some of you more "in the know", and you did just that. I did not want to imply anything different, and I appreciate all of the responses; thank you!

From talking to the plasterer, he wants to lower the pH to zero. I just can't imagine what that would do to lights, rope anchors, grab bars or anything else metallic! Seems very aggressive to me!

OK, next question: How would be the best way to get the pH back up in range from zero? The Pool Calculator only goes to 6.4 (on my iPhone anyway!), and shows Borax, but I doubt that the plasterer is going to use Borax!
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
Well, when I've done acid washings I neutralize the waste water collection pool with 2 lbs of baking soda per one gallon of 3x.x MA used. I haven't been concerned with anything but relatively "neutral" pH though, to send to waste, which, in my case is the woods, down the hill. I've never even gotten a tingle on my "delicate as an orchid" skin, spending hours in the somewhat neutralized waste pool, while standing down in the pool while doing more acid washing in spots. This will raise the TA MAJOR but as long as it is going to waste and you are starting over with fresh fill water, before doing your specialized process, I wouldn't think that should be of any concern for your part of the job. :)

OR ARE THEY NOT DRAINING THE POOL? THAT IS A DIFFERENT CONSIDERATION.

I have very alkaline soil to begin with but the plants are all indigenous to our alkaline soil. Nothing has suffered, down the hill, over many years, and the plants tell me they are very grateful for the additional water, especially during droughts. :mrgreen: Our tap water, and waste from the pool, has far less TA than the native soil.

The draining from the pool, after the "wet acid wash" should be handled properly by the plaster co doing the job. I'll bet they have all the ins and outs of waste water disposal for the area, unless they are leaving you with the waste water. Is that the case?

gg=alice
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
simicrintz said:
Just to clarify my earlier post where I said some of you were predictable ( :oops: ): What I meant, even if it did not come across that way, was that I had hoped (expected) responses from some of you more "in the know", and you did just that. I did not want to imply anything different, and I appreciate all of the responses; thank you!
I took it as quite enduring and friendly. :sun:
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
Take any numbers with a grain of salt. I could be off by kazillions. :roll:

If you are left with the water after "filled acid wash" is done, just looking at it at a very simplistic angle.... if you have to neutralize the water, disregarding other values in the Calculator, adding 900 oz of washing soda or soda ash will raise the pH around 6 and increase TA by 200. Let's let chemgeek weigh in here. I'm just doing a rough estimate, late at night, after doing a hours of paper work. :rant: And I'm a blond after all, with "old timers" and a few wines under my belt (only way I can stand to sit still to do this indoor Crud). I'd much prefer the broom and mop to this *********************!!!!!!!!!!!!!!!!

Just looking at the Pool Calculator it seems pretty straight forward to me, looking at it in my blond daze. Of course you know what your equipment can handle.

Although using the Pool Calculator, at the top section, to raise pH from 0 to 3, all other numbers 0, Calculator calls for 57xx oz of washing soda or ash, which, when you go to bottom, indicates that much addition will raise pH by 41.xx and TA by 13xx.

La de dah.........

ChemGeek, where are you? :wave: :wave: :wave:

Better still................ Have them drain the water and refill and do what you do best.

gg=alice :slidehalo:
 

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