Where is CO2 coming from?

[JamesW]

If the TDS is mostly as estimated, the salinity reading from a conductivity meter is estimated to be about 1.50 to 1.78 grams per liter (1,500 ppm to 1,780 ppm) in the salinity setting or about 2,100 ppm to 2,600 ppm in the total dissolved solids setting.

If the conductivity meter reads higher than these numbers, then there are likely to be unaccounted for dissolved solids.

If the readings are in this range, then you have likely accounted for most of the dissolved solids.

In addition to the fill water, you can do the same process for the pool water to see if you can find a suitable balanced equation.

You would include all known additions like chlorine and acid since you know how much of these you have added.

For example, you know how much acid is used, so you can calculate the number of moles of sulfate added by the acid that was added etc.

 

[JamesW]

Concentrations are usually not specified on the bottles but I am assuming around 30% based on some bottles I saw here and there by chance. My pool is 80000 liters. I spend around 6 bottles in a season. How do I calculate sulphate ppm?

40% sulfuric is about 4.07 moles per liter.

120 liters is 488.4 moles.

488.4 moles of sulfate at 96.06 g/mol = 46,915.7 grams sulfate.

That will raise the sulfate by about 585 ppm.

Sulfates should be kept below about 300 ppm as much as possible.

Sulfate Test Kit - HI38000

The HI38000 is a chemical test kit that uses a turbidimetric method to measure sulfate. The HI38000 is supplied complete with all of the reagents and equipment necessary to perform approximately 100 tests. Pre-made reagents for ease of use All reagents marked with expiration date and lot number...

hannacan.com

Sulfate Test Kit

This kit tests for Sulfate using the Octa-Slide 2 Comparator. Range and sensitivity is 20, 40, 60, 80, 100, 120, 160, 200 ppm SO42-.

lamotte.com

40% sulfuric acid - 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

http://www.spiespool.com/blog/wp-content/uploads/2015/07/SDS-Sulfuric-Acid-Non-Fume-Acid-from-Brenntag1.pdf

http://sentryindustries.net/wp-content/uploads/2016/12/MSDS-Sulfuric-Acid.pdf

https://labelsds.com/images/user_uploads/Poolsure%20Sulfuric%20Acid%20SDS%206-30-15.pdf

https://poolwaterproducts.com/msds/vendor/Hasa/Sulfuric_Acid.pdf

You are probably adding about 48Kg (106 pounds) of sulfate to the pool per year.

 

[JamesW]

It seems the bottles I am buying are 20 liters each and weigh 25kg (do we use the volume or mass for calculations?) Concentrations are usually not specified on the bottles but I am assuming around 30% based on some bottles I saw here and there by chance. My pool is 80000 liters. I spend around 6 bottles in a season.

That will lower the TA by a total of about 530 ppm, which seems a little bit high even considering the high TA fill water at about 300 ppm.

If you lower the TA from 300 to 60, that's 240 ppm.

If you get 100% evaporation, then you do that twice for 480 ppm.

How much evaporation do you get?

To need 530 ppm TA reduction, you would need to have evaporation of 120% of the volume, which is 96,000 liters per year, which is an average of 263 liters per day, which is about 4.7 mm per day.

 

[fanis.merk]

That will lower the TA by a total of about 530 ppm, which seems a little bit high even considering the high TA fill water at about 300 ppm.

If you lower the TA from 300 to 60, that's 240 ppm.

If you get 100% evaporation, then you do that twice for 480 ppm.

How much evaporation do you get?

To need 530 ppm TA reduction, you would need to have evaporation of 120% of the volume, which is 96,000 liters per year, which is an average of 263 liters per day, which is about 4.7 mm per day.

I have 250-500 liters of evaporation and is inline with my water level tests. I have 50m2 surface area and lose around half a cm to 1cm per day to evaporation and splash. This happens in around 5 month. Splash from children jumping is a very big problem in overflow pools as the water is at deck level. Also are you using 30% or 40% acid concatenation?

 

[JamesW]

Also are you using 30% or 40% acid concatenation?

120 liters of 30% H₂SO₄ are roughly equivalent to 85 liters of 31.45% hydrochloric acid.

30% sulfuric acid - 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

31.45% hydrochloric acid - 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

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]

Maybe consider getting a salt test meter and a sulfate test to monitor your fill water and your pool water.

Sulfate Test Kit

This kit tests for Sulfate using the Octa-Slide 2 Comparator. Range and sensitivity is 20, 40, 60, 80, 100, 120, 160, 200 ppm SO42-.

lamotte.com

Sulfate Test Kit - HI38000

The HI38000 is a chemical test kit that uses a turbidimetric method to measure sulfate. The HI38000 is supplied complete with all of the reagents and equipment necessary to perform approximately 100 tests. Pre-made reagents for ease of use All reagents marked with expiration date and lot number...

hannacan.com

 

[JamesW]

PC60 Premium Multiparameter (pH/EC/TDS/Salinity/Temperature) Pocket Tester/Meter Kit-Apera Instruments

The Apera Instruments PC60 Multi-parameter Tester/Meter simply tests pH/EC/TDS/Salinity/Temperature for regular aqueous solutions such as hydroponics, aquaculture, pools& spas, tap/drinking water, water treatment, cooling towers, etc.

aperainst.com

https://www.taylortechnologies.com/...ivitysalinitytds-myron-l-ultrapen-pt1--M-6555

Ultrapen™ PT1

The Ultrapen™ PT1 is an accurate and reliable pocket water tester for measuring Conductivity, TDS, Salinity and Temperature.

www.myronl.com

Salt/TDS/Conductivity/Temp TRACER PockeTester™

Quick, Accurate, Digital Measurement! The electronic Salt TRACER PockeTester™ measures the Sodium Chloride level in salt water pools with a range from 0 to 9,999 ppm. TDS is measured from 0 to 9,999 ppm and Temperature from 32.0° to 149°F.

lamotte.com

Salt/TDS/Conductivity/Temp TRACER PockeTester™

The electronic Salt TRACER PockeTester™ measures the Sodium Chloride level in salt water pools with a range from 0 to 9,999 ppm. TDS is measured from 0 to 9,999 ppm and Temperature from 32.0° to 149°F.

lamotte.com