Can I put salt in my saltwater pool while Shocking it(Algie)

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BenniefromSA

Can I put salt in my saltwater pool while Shocking it(Algie)

Postby BenniefromSA » Sat 03 Jan, 2009 05:56

I pool is light green, and i have just shocked it with HTH Shock-it. Would you think i can through the 25Kg salt in at the same time, or wait?

Thank you


chem geek
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Can I put salt in my saltwater pool while Shocking it(Algie)

Postby chem geek » Sat 03 Jan, 2009 15:37

If your pool is truly low in salt, then you can add salt at any time, but you need to use external sources of chlorine such as chlorinating liquid to shock your pool to kill the algae; you can't kill the algae in a bloom fast enough with an SWG alone.. How much chlorine you need depends on your pool's Cyanuric Acid (CYA) level. See Defeating Algae in the Pool School at Trouble Free Pool for more info.
lonestar
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Can I put salt in my saltwater pool while Shocking it(Algie)

Postby lonestar » Wed 28 Jan, 2009 11:16

A salt pool already has a high TDS and has a hard time keeping everything in solution.

As shocking has a tendency to push metals out of solution and salt (even when labeled as pure) can contain trace amounts of metals, it is recommended that you add salt at a different time from shocking.

Have your PH and ALK within range when adding salt, and brush until it is completely dissolved. Ive seen any of these situations result in staining (from either trace metals already in the water or in the salt.)
chem geek
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Can I put salt in my saltwater pool while Shocking it(Algie)

Postby chem geek » Wed 28 Jan, 2009 20:52

A salt pool with 3000 ppm salt does not have a hard time keeping everything in solution. Sea water has closer to 35,000 ppm salt and the saturation level of salt in water is close to 400,000 ppm.

As for shocking, it isn't the chlorine, but rather the high pH from using a hypochlorite source of chlorine that would cause metals to potentially stain as metal oxides. If one is going to be shocking with a Free Chlorine (FC) level above 10 ppm, one can simply lower the pH first (to 7.2 or so) before shocking and avoid any possible metal staining or calcium carbonate precipitation (i.e. scaling).

Also, if there are trace amounts of metals in salt, once you add the salt the metals will be there and stay there unless you add a metal sequestrant so one would have a problem anytime after salt was added. In other words, any problem is not related to shocking close to when one adds salt unless such salt and potential metal ions are not thoroughly mixed in the water (i.e. concentrated in the same spot where you add chlorine to shock).

I agree with you that one should lower the pH first before shocking with significant amounts of a hypochlorite source of chlorine, but that's generally true even in non-salt pools in order to avoid cloudiness or scaling.

Richard

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