No drain 0 TA acid wash advice and questions.

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D

dradam

LifeTime Supporter
Mar 10, 2013
255
Maryland
Pool Size
19000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Looking to do a no drain acid wash before startup this spring. My WetEdge luna quartz finish has become hazy over the past 10 years. Inspection under water seems to show that the plaster between the agregate has overgrown the agregate dulling it. I suspect this is more just a problem with the initial plastering and that acid wash may not help but I want to try it none the less.

Trying to put together what I have read here on TFP threads. Would love a good "how to" on this in pool school.

I plan to:
Bring TA to 0. Estimating about 4-5 gallons of MA-Starting TA 100 then maintain for a week with wire brushing.

Questions:
1) How much soda ash (lbs) to bring it up? Can any one recommend a calculator for this. Is all soda ash the same % ?

2) While I can lift out my pool light, a stainless ring is embedded in the pool wall. Ignore it? coat it with petrolium jelly?

3) Calcium dust I will vacuum when running , but I see that Hardness will increase. Won't I need to drain and refill to lower It? If so kinda defeatd the no drain plan ?

Thanks In advance, would appreciate and insights and advice.
 
You are getting close to drain territory if your CH is that high. The no drain acid wash will raise the CH levels since it will put any calcium deposits back into solution. Lowering the CH to 250 with pH maintained between 7.0-7.4 will probably give you the same results as an acid wash and will put the calcium deposits back into solution. If your CH is that high when you open I would try lowering the CH and pH first before trying the acid wash, since it sounds like you may need to do a partial drain anyway.
 
zea3 said:
You are getting close to drain territory if your CH is that high. The no drain acid wash will raise the CH levels since it will put any calcium deposits back into solution. Lowering the CH to 250 with pH maintained between 7.0-7.4 will probably give you the same results as an acid wash and will put the calcium deposits back into solution. If your CH is that high when you open I would try lowering the CH and pH first before trying the acid wash, since it sounds like you may need to do a partial drain anyway.
Click to expand...
Thank you ,I will check th CH at opening.
 
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dradam said:
Bring TA to 0. Estimating about 4-5 gallons of MA-Starting TA 100 then maintain for a week with wire brushing.
Click to expand...
1 gallon is 26 ppm. So, about 4 gallons is estimated.

Don't wait a week, maybe 12 hours maximum.
1741446805625.png

dradam said:
1) How much soda ash (lbs) to bring it up? Can any one recommend a calculator for this. Is all soda ash the same % ?
Click to expand...
Don't use soda ash, use baking soda.

Estimate 22 lbs.

1741446943155.png

1741447127744.png

PoolMath

Discover the calculator behind the perfect pool, PoolMath. Dealing with pools has allowed TFP to become the original authors of the best calculator on the net.
www.troublefreepool.com
 
JamesW said:
1 gallon is 26 ppm. So, about 4 gallons is estimated.

Don't wait a week, maybe 12 hours maximum.
View attachment 631143


Don't use soda ash, use baking soda.

Estimate 22 lbs.

View attachment 631144

View attachment 631145

PoolMath

Discover the calculator behind the perfect pool, PoolMath. Dealing with pools has allowed TFP to become the original authors of the best calculator on the net.
www.troublefreepool.com
Click to expand...
Thank you. Won't baking soda bring the TA too high compared to soda ash ?
 
dradam said:
Won't baking soda bring the TA too high compared to soda ash ?
Click to expand...
No, just use the correct amount of baking soda and the pH will recover.

The pH will go to about 6.8 right away and then you have to wait about 24 hours for the carbon dioxide to offgass and the pH will be over 7.2.

It is basically the same result either way, but sodium carbonate is much more likely to cause problems by combining with calcium for form calcium carbonate scale and cloudiness.

Sodium carbonate also risks overshooting the pH by a lot whereas baking soda can't go over a pH of 8.3.
_____________________________________________________________________________________________

HCO3- + H+ --> H2O + CO2

Bicarbonate (Baking Soda) + Hydrogen Ion (Acid) --> Water + Carbon Dioxide.
_____________________________________________________________________________________________

CO32- + 2H+ --> H2O + CO2

Carbonate (Soda ash) + 2Hydrogen Ions (Acid) --> Water + Carbon Dioxide.
_____________________________________________________________________________________________

Ca2+ + CO32- --> CaCO3

Calcium ions + carbonate -- Calcium carbonate.
_____________________________________________________________________________________________
1741617614242.png

1741617526308.png

1741617824901.png

1741618212453.png

graph y = 100/((10^(10.3-x)) + 1) and y = 100 - (100/((10^(10.3 - x)) + 1)), x from 8 to 12 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.
www.wolframalpha.com www.wolframalpha.com

1741624842600.png


graph y = 100/((10^(6.35-x)) + 1) and y = 100 - (100/((10^(10.3 - x)) + 1)), x from 4.55 to 12 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.
www.wolframalpha.com www.wolframalpha.com

1741624950016.png

graph y = 100/((10^(6.35-x)) + 1) and y = 100 - (100/((10^(10.3 - x)) + 1)), x from 4.55 to 12 - Wolfram|Alpha

Wolfram|Alpha brings expert-level knowledge and capabilities to the broadest possible range of people—spanning all professions and education levels.
www.wolframalpha.com www.wolframalpha.com
 
Last edited:
This shows the percentage of bicarbonate vs. pH.

The maximum is at about a pH of 8.25, which is why the pH won't go over that number when adding baking soda.

Adding baking soda always pushes the pH towards 8.3.

If you add 1,585 lb of baking soda to a 19,000 gallon pool (1% solution), the pH should end up at 8.3 regardless of where the pH started.

If you add baking soda while the pH is over 8.3, the pH will go down because some of the bicarbonate needs to convert into carbonate which releases a hydrogen ion.

HCO3- --> H+ + CO32-. (pH over 8.3).

HCO3- + OH- --> H2O + CO32-

Bicarbonate + Hydroxide ion --> Water + Carbonate.

When the pH is low (below 8.3), the bicarbonate converts into carbon dioxide, which raises the pH.

HCO3- + H+ --> H2CO3 --> CO2 + H2O.

When the pH is 8.3, any added bicarbonate mostly stays as bicarbonate with a tiny amount becoming carbon dioxide and an equal (Molar) amount becoming carbonate, which exactly offsets any pH change.

2HCO3- --> CO32- + CO2 + H2O

1741618575052.png
You can use the formulas to calculate the percentage of bicarbonate vs. carbon dioxide or carbon dioxide vs. bicarbonate.

100÷(1+10^(6.35 – 8.3)) = 98.890% bicarbonate vs. carbon dioxide.

100-(100÷(1+10^(6.35 – 8.3))) = 1.109% carbon dioxide vs. bicarbonate.
 
Last edited:

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JamesW said:
This shows the percentage of bicarbonate vs. pH.

The maximum is at about a pH of 8.25, which is why the pH won't go over that number when adding baking soda.

Adding baking soda always pushes the pH towards 8.3.

If you add 1,585 lb of baking soda to a 19,000 gallon pool (1% solution), the pH should end up at 8.3 regardless of where the pH started.

If you add baking soda while the pH is over 8.3, the pH will go down because some of the bicarbonate needs to convert into carbonate which releases a hydrogen ion.

HCO3- --> H+ + CO32-. (pH over 8.3).

HCO3- + OH- --> H2O + CO32-

Bicarbonate + Hydroxide ion --> Water + Carbonate.

When the pH is low (below 8.3), the bicarbonate converts into carbon dioxide, which raises the pH.

HCO3- + H+ --> H2CO3 --> CO2 + H2O.

When the pH is 8.3, any added bicarbonate mostly stays as bicarbonate with a tiny amount becoming carbon dioxide and an equal (Molar) amount becoming carbonate, which exactly offsets any pH change.

2HCO3- --> CO32- + CO2 + H2O

View attachment 631477
You can use the formulas to calculate the percentage of bicarbonate vs. carbon dioxide or carbon dioxide vs. bicarbonate.

100÷(1+10^(6.35 – 8.3)) = 98.890% bicarbonate vs. carbon dioxide.

100-(100÷(1+10^(6.35 – 8.3))) = 1.109% carbon dioxide vs. bicarbonate.
Click to expand...
Thank you for this detailed and thorough explaination. Bicarb will be much easier for me to source.
 
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