Is the salt in SWG harmful to Automatic pool covers?

isabelo

Well-known member
Sep 22, 2014
65
0
San Ramon, California
#1
I am playing with the idea of putting SWG but my pool builder is discouraging me from going that route. This is what he said - " . . . Salt is bad for the cover. The hot weather makes it tougher to keep up with chlorine, but it’s not worth the destructive nature of salt. Just keep up with your chlorine. Salt is never recommended for cover pools. . . ." . Is there validity to what he said?

I am currently using Liquid Chlorine (BBB method). i am just wondering if the benefit of not hauling bleach or LC is worth switching to SWG.
 

jblizzle

Mod Squad
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May 19, 2010
41,193
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Tucson, AZ
#2
per usual, the pool builders are full of half truths.

The slightly higher salt levels of a SWG pool (3200ppm vs up to 1000+ppm in a "bleach" pool) can be a little more corrosive, but most people do not notice a problem.

The hot weather thing is just bogus. If you have the recommended CYA levels, the SWG will have no problems maintaining adequate FC. They seem to be working just great in the 1000s of SWG pools in the AZ heat/sun.

I have never heard the argument against salt for a covered pool.
 

JasonLion

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May 7, 2007
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Silver Spring, MD
#3
Some automatic pool covers have an aluminum frame that is in direct contact with the water. If you have one of those, there is a possibility of a galvanic reaction causing degradation of the aluminum when salt is added to the pool. This problem does not affect everyone and can be mitigated by using a zinc anode connected to the bonding system and buried in damp soil.
 

isabelo

Well-known member
Sep 22, 2014
65
0
San Ramon, California
#4
My Automatic pool cover rails are located between the underside of the coping and just above the tiles (for wateline) so there is at least 3" of separation. However, there would be water splashing into the rail when pool is being used and most probably water could temporarily be trapped inside the rails and hopefully will drain towards the cover storage vault where there is a drain pipe. I wish there is a commercial and safe dispensing systems available for liquid chlorine.
 

JasonLion

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May 7, 2007
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#5
Splashing will not support a complete electrical circuit. If the aluminum only comes in contact with the water through splashing there shouldn't be any galvanic reaction and thus should not be a problem.
 

chem geek

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TFP Expert
Mar 28, 2007
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San Rafael, CA USA
#8
Saltwater splash-out onto aluminum railing can corrode the material without being immersed into the water as shown in this post. This isn't galvanic corrosion between dissimilar metals but standard metal corrosion from oxygen in the air accelerated by the high conductivity of the saltwater on the rail. The electrical circuit is localized due to differences in adjacent areas (in metal consistency or salt concentration). This may not happen to the same extent with under-track railing due to its ability to drain. A sacrificial anode will reduce corrosion rates regardless of corrosion type because it puts a negative voltage on the metal that makes it more difficult for the solid metal to corrode as positive metal ions.
 

isabelo

Well-known member
Sep 22, 2014
65
0
San Ramon, California
#9
Saltwater splash-out onto aluminum railing can corrode the material without being immersed into the water as shown in this post. This isn't galvanic corrosion between dissimilar metals but standard metal corrosion from oxygen in the air accelerated by the high conductivity of the saltwater on the rail. The electrical circuit is localized due to differences in adjacent areas (in metal consistency or salt concentration). This may not happen to the same extent with under-track railing due to its ability to drain. A sacrificial anode will reduce corrosion rates regardless of corrosion type because it puts a negative voltage on the metal that makes it more difficult for the solid metal to corrode as positive metal ions.
Thank you all for your inputs. Considering chem geek's point of view, I'll stick with bleach/LQ and will figure out if a Liquidator or a Stenner system would work fine in my pool configuration and location (direct sun most of the day). For the time being, I'll take advantage of manually hauling bleach/LQ to strengthen the abdomen, biceps, and knees.
 

dfahrion

Bronze Supporter
Oct 18, 2013
89
0
Iowa
#10
As jblizzle mentioned a bleach pool contains salt too, although typically not as high of levels as a SWG pool. So as I learned the hard way corrosion is still something to worry about when just using bleach. Our autocover drum corroded through this year such that we couldn't open the cover until it was replaced. The builder said we need to be rinsing everything off with the hose on a regular basis to prevent that from happening again, and if we were to switch to SWG just rinse more often. Every time you roll up the cover a small amount of pool water drips on the ends of the drums and eventually the corrosion from that caused it to snap in two.
 

jblizzle

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May 19, 2010
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Tucson, AZ
#11
Not just bleach ... any form of chlorine adds salt to the water. While some of the solid forms may add less salt, they add other things which are usually worse.
 

isabelo

Well-known member
Sep 22, 2014
65
0
San Ramon, California
#12
As jblizzle mentioned a bleach pool contains salt too, although typically not as high of levels as a SWG pool. So as I learned the hard way corrosion is still something to worry about when just using bleach. Our autocover drum corroded through this year such that we couldn't open the cover until it was replaced. The builder said we need to be rinsing everything off with the hose on a regular basis to prevent that from happening again, and if we were to switch to SWG just rinse more often. Every time you roll up the cover a small amount of pool water drips on the ends of the drums and eventually the corrosion from that caused it to snap in two.
How and where do you rinse the cover drum? Do you rins it when the cover is on the pool or when it is rolled onto the drum? We have a walk-on cover on the vault. The walk-on cover is same material as our coping supported by heavy gauge stainless steel bracket and trays. Each tray is ~80-100lbs (Three River flagstones and concrete). It'll be a laborious task to do this rinsing. Oh, well - another thing to worry about. Thanks for the heads up.
 

dfahrion

Bronze Supporter
Oct 18, 2013
89
0
Iowa
#13
Our vault cover is a simple aluminum one, but I was told to just spray a hose into the corners where the cover feeds into it, I have just enough gap in the corners to get a good spray in there without having to open the vault. I believe I want the cover unrolled (pool closed) before doing that so I can hit as much of the drum as possible, but I might be wrong on that. Since I couldn't remember which way they told me I just do it once with the pool open (and hit the tracks too while I have the hose out), and again into the corners of the vault after I close it.
 

isabelo

Well-known member
Sep 22, 2014
65
0
San Ramon, California
#14
Our vault cover is a simple aluminum one, but I was told to just spray a hose into the corners where the cover feeds into it, I have just enough gap in the corners to get a good spray in there without having to open the vault. I believe I want the cover unrolled (pool closed) before doing that so I can hit as much of the drum as possible, but I might be wrong on that. Since I couldn't remember which way they told me I just do it once with the pool open (and hit the tracks too while I have the hose out), and again into the corners of the vault after I close it.
Thanks dfahrion. I appreciate the heads-up. The pool cover manufacturer should have stressed this out after they installed it, but then again maybe they did in the myriad of documentation I got from the PB. It's overwhelming.