Salt generator and calcuim hardness

Total hardness and calcium hardness in pool water.
Scale, calcium buildup, hard water and scaling problems.
park beam
Pool Newbie
Pool Newbie
Posts: 2
Joined: Sat 28 Mar, 2009 08:59
My Pool: 15000g, in ground, diamond brite
Location: South Florida

Salt generator and calcuim hardness

Postby park beam » Sat 28 Mar, 2009 09:13

I am considering adding a Intermatic chlorine generator to my in ground pool. I had the pool resurfaced several years ago, and I am told that the contractors probably used calcuim to get the diamond brite to harden more quickly. My hardness is currently in the 500 range. Last year I took the level down 50% and got the hardness down to the 300 range.

Living in South Florida (Deerfield), we do get rain regularly in the summer, but I added 100-200 gal of city water every 7-10 days this winter.

Am I making a mistake thinking a chlorine generator will work without lots of extra problems. I am currently not getting a lot of buildup on tile or other surface areas.

Please advise and maybe I can cancel the order


chem geek
Pool Industry Leader
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Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Salt generator and calcuim hardness

Postby chem geek » Sat 28 Mar, 2009 12:14

You can operate a saltwater chlorine generator (SWG) system with 300 ppm Calcium Hardness (CH) without problems. Just have the Total Alkalinity (TA) on the low-side, around 80 ppm, and keep the pH from getting above around 7.7. Have the Cyanuric Acid (CYA) level at around 70-80 ppm and maintain the Free Chlorine (FC) at 4 ppm. Finally, if you want to further reduce scaling in the salt cell, use 50 ppm Borates in the pool to act as an additional pH buffer (it's also a mild algaecide). You can use The Pool Calculator to calculate the saturation index which for the numbers above will be around -0.2 which is slightly corrosive. Just try and keep this index slightly less than 0. You still have some more room for the CH to climb to around 500 ppm before the index gets above 0. Also check out Water Balance for SWGs . For an extreme view on the downside of salt pools, see this blog . The experiences of people with SWG pools varies. Most problems can be mitigated, but don't use soft limestone or low-grade stainless steel or aluminum without doing sealing or using a sacrificial anode, etc.

Richard
park beam
Pool Newbie
Pool Newbie
Posts: 2
Joined: Sat 28 Mar, 2009 08:59
My Pool: 15000g, in ground, diamond brite
Location: South Florida

Salt generator and calcuim hardness

Postby park beam » Wed 08 Apr, 2009 10:01

Hey geek

Thanks for the reply about hardness......I used 1lb of Super Sequia Sol and got hardness down to 300+.....

interested in all you comments about TA and PH and what effect Borax has.....is it a buffer besides raising PH without raising TA.....based on your comments I should keep salt level as low as possibe that will work with my generator (Intermatic Salt Chlorine Generator PE40K240V)...I would like to get TA down as you recommend for longer cell life...

SI was -0.25 which I take is OK. TA was120 and PH 7.4.....I have been adding Acid to drop TA and have set up a aereator with a submersible pump and hose and pvc pipe.

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