Which chemicals are used in salt-water pools?

[MoD1977]

On 4/24/2020 at 8:43 AM, Bagwain said:

You can order at the pool shop up near Route CC bar on Siam Country Club.

I have bought there before!

Was there today and got a 25kg bag for 1200.- Baht

Thank you for the tip Bagwain.

[samtab]

Hello,

 

If salt is still chlorine, how possible that someone has skin problems when swimming in declared chlorine water but not when swimming in salt pool ?

 

thank you.

 

[Susco]

On 4/14/2020 at 8:41 AM, Bagwain said:

Depending on the size of your pool, will dictate how much acid to use. You can use Hydrauchloric acid or dry cyrstal acid (looks like rock salt). As a guide a 100,000 litre pool would use about 2 litres of Hydaucloric acid a week.

 

Strange but in my 60.000 liter salt water pool I haven't added 2 liter in the past year, and I check it frequently with a digital Ph meter, and it's always between 7 and 7.5.

 

My TA is also very stable, though it's low at between 50 and 60 ppm.

 

My well water is very low in Ph, at about 4.5, so that may be the reason

 

During rain season, when Ph tends to drift higher, I also add chlorine tablets in a floating duck, as the chlorinator otherwise can't keep up with the excessive water

 

 

Edited July 15, 2020 by Susco

[Bagwain]

4 hours ago, samtab said:

Hello,

 

If salt is still chlorine, how possible that someone has skin problems when swimming in declared chlorine water but not when swimming in salt pool ?

 

thank you.

 

Mainly due to acidic water! Salt water is also better for the skin! 

 

[Charly2008]

I did battle black algae a while now, lowered the PH, added black algaetrine as per instruction kept it sitting for a 20 hours without pump running, then brushed out the algae vacuum the pool and did a long backwash of the filter.

during this action my T/A dropped to 25ppm therefore I added some kg sodium bicarbonate, but that will rise my PH again. I struggle to get the T/A above 80 with the PH between 7 - 7.2. the pool has 70 cbm water and runs on purapool oxygen. I add a week approx 2 L HCL and 2-3kg sodium bicarbonate.

Another issue is the calcium level, whenever I added calcium it somehow crystallized, which resulted in white flakes below the water outlets at the pool wall and around the water outlets at the pool floor. a pool company advised me to not add calcium anymore, have now level below 50 and I thought during brushing out the algae that the grouting is getting deeper.

 

I am would be happy for any suggestion.

 

[Bagwain]

5 hours ago, Charly2008 said:

I did battle black algae a while now, lowered the PH, added black algaetrine as per instruction kept it sitting for a 20 hours without pump running, then brushed out the algae vacuum the pool and did a long backwash of the filter.

during this action my T/A dropped to 25ppm therefore I added some kg sodium bicarbonate, but that will rise my PH again. I struggle to get the T/A above 80 with the PH between 7 - 7.2. the pool has 70 cbm water and runs on purapool oxygen. I add a week approx 2 L HCL and 2-3kg sodium bicarbonate.

Another issue is the calcium level, whenever I added calcium it somehow crystallized, which resulted in white flakes below the water outlets at the pool wall and around the water outlets at the pool floor. a pool company advised me to not add calcium anymore, have now level below 50 and I thought during brushing out the algae that the grouting is getting deeper.

 

I am would be happy for any suggestion.

 

1st - what surface has the pool got?

2 nd - have you tested the make up water for calcium? (Most water "especially ground" already has high calcium)

3 rd - you need to test the make up water for T/A & pH as well!

 

Try and get the T/A to 80 - 120 or little higher as the acid pH control will always lower it! Use soda ash in between S/Bi-carb for economics!

 

Every pool has its own personality & you need to learn it. Just like a Wife!! 5555

[Charly2008]

appreciate your quick response, I do my measurements with the COLORQ LaMotte, with make up water I guess you refer to the city water I use to refill, am I correct?

following answers:

1st. pool surface 50 sqm with 1.4m depth

2nd. for the calcium level the LaMotte displays just "Lo"

3rd. for the T/A ( Alkalinity ) it displays 34 and for the PH "Lo"

 

todays readings for the pool water is: FCL 1.42 / TCL 1.42 / PH 7.3 / ALY 40 / CH 27 / CYA 47 / <deleted> 2340  I did add today 3kg S/Bi-carb, now I need to worry that my PH rises and the black algae coming back, correct?

the city water / make up water readings: FCL 1.21 / TCL 1.21 / PH "Lo" / ALY 34 / CH "Lo" / CYA 30

 

what do you think about the calcium level, as per pura pool it should be between 200 to 300 I am way off to low.

[Bagwain]

6 hours ago, Charly2008 said:

appreciate your quick response, I do my measurements with the COLORQ LaMotte, with make up water I guess you refer to the city water I use to refill, am I correct?

following answers:

1st. pool surface 50 sqm with 1.4m depth

2nd. for the calcium level the LaMotte displays just "Lo"

3rd. for the T/A ( Alkalinity ) it displays 34 and for the PH "Lo"

 

todays readings for the pool water is: FCL 1.42 / TCL 1.42 / PH 7.3 / ALY 40 / CH 27 / CYA 47 / <deleted> 2340  I did add today 3kg S/Bi-carb, now I need to worry that my PH rises and the black algae coming back, correct?

the city water / make up water readings: FCL 1.21 / TCL 1.21 / PH "Lo" / ALY 34 / CH "Lo" / CYA 30

 

what do you think about the calcium level, as per pura pool it should be between 200 to 300 I am way off to low.

What is your pool surface & & if tiles what is the state of the grout. (Important)

Standard pool reading ranges. (Keep it simple)!

Cal 200 - 300 (Most don't worry in Thai)

T/A 80 - 120

pH 7.2 - 7.8 (Salt pool best lower range around 7.2) This would mean approx 2/3 litre of acid divided by 2 twice a week! Trial & error.

Cl 1.2 - 3 ppm.

 

Don't add more than 1 kg of S/Bicarb at a time. Make sure it is dissolved in a bucket 1st.

You will get false readings if you don't. T/A has to be raised slowly. Once you have the range then next day do the pH test! Or later in afternoon!

 

Once you get to know the personality of ya pool you can then set a plan for chemicals! 

 

[Charly2008]

I did add the S/Bicarb 1 kg at a time and my T/A came up to 88, but the PH came up to 7.6 as well which is within the acceptable range. Nevertheless I worry about the black algae with this PH value. Plan to add later today some HCL to get the PH lower. Will update here further it may helps others as well.

 

Now I start to add calcium flakes, the current value is just 44 quite far from 200 I will see.

 

Thanks again for your suggestions and sharing your experience, the way is long and steep, but sooner or later I shall reach the finish line.

 

Cheers,

Charly