new ? on adding salt to non-SWG AG pool

[GraceByDesign]

Ok, no pool yet, but want to be all ready when we get it!

We will be getting an AG pool, Doughboy, steel (well, not aluminum or resin). I had decided against getting a SWG after reading here about salt causing corrosion of metals.
So ...
Is it really ok to add salt, say 1000-15000 ppm, to an AG pool? Will that concentration not cause corrosion? Seems like the talk in the other thread covered why to put salt, what type, how much, but did not address the Should you or Shouldn't you issue. And if this is ok, I'd like to know why, when it is generally said not to do SWG on AGPs? I would prefer not to do anything foolish to my pool if I can avoid it! (hence reading so far in advance of our purchase!)

TWIA (Thanks WAAAY in advance)

Grace

Avid reader of this forum
but alas, no pool... yet!

[waste]

Grace, the problem is not the swg, but the salt itself. Any splashout on the exterior of the pool will contain salt. As the water evaporates and leaves the salt behind, the lethal (to metal) 6000 ppm can be reached and start rusting the walls. If you were dilligent to hose off the walls after every swim session, you could probably avoid the problem - however, if you get lazy or if someone uses the pool when you're not there and doesn't rinse it completely, there is a fair chance of your pool rotting out long before it's time.
Now for the news you really don't want to hear:
Using bleach will raise the salinity of the pool (although it takes a while) - because bleach contains salt, which doesn't evaporate so just keeps building. Therefore, whichever way you go, you'll eventually have to deal with a saline pool, unless you partially drain a bleach pool on a regular basis. The real /? is 'at what saline level is splashout safe for an AG?' I don't know the answer, I'm sure strength of bleach (%) and amount added vs. pool volume and backwashing/ winter draining all come into play - perhaps one of the chemists will see this and respond (Poolsean would also be a good source, I got the 6000 ppm bit and evaporation thing out of one (or more) of his posts on the old forum) Hopefully, this helps a bit, sorry I can't be more specific but maybe this post will spark the answers that I can't give - Waste

ps, swimming in non saline water is better than not being able to swim because the walls collapsed!

[ChuckD]

You'd think the pool industry would've taken this saline issue into account by now when they design pools.

Just thinking out loud....

[Poolsean]

resin or poly walls instead of aluminum or steel...
It's more expensive but will prevent any damage from corrosion.

[Mark_WATERMAID]

[QUOTE=waste]Grace, the problem is not the swg, but the salt itself. Any splashout on the exterior of the pool will contain salt. As the water evaporates and leaves the salt behind, the lethal (to metal) 6000 ppm can be reached and start rusting the walls.

I got the 6000 ppm bit and evaporation thing out of one (or more) of his posts on the old forum) Hopefully, this helps a bit, sorry I can't be more specific but maybe this post will spark the answers that I can't give - Waste

I would like to nip this notion of the "Lethal 6000 ppm" in the bud. I was the one in the old post that expressed my concern for above ground pools using a salt system. I explained that splash out or leaks would run down the side of the pool and get trapped in the bottom track of the pool where they would evaporate. This evaporation would create a concentrated salt residue, which would lead to corrosion issues. NEVER did I say that there was a magic threshold of 6000 ppm. IF 6000-ppm salt level caused that much trouble, there would be thousands of Watermaid pools around the world that would have died from this "Lethal" level. The reality is, Watermaid has used this level for 35 years and there is no "threshold" of corrosion or "lethal" level at 6000 ppm. The levels that I was talking about are those that we see on the sides of our cars in the winter (at least up here in Canada). A level more concentrated than ocean water and that IS a problem.

By increasing salt levels in a pool, you make the water more conductive. It is this increased conductivity that leads to corrosion. There is no magic level where the switch gets turned on and your pool rusts. It is simply an ever-increasing conductivity, which follows salt level. If we used distilled water and put absolutely nothing in it, the conductivity would be 0. If you add anything to it, it becomes more conductive. Dissolved solids increase conductivity. Where the big scare comes in is in the numbers that we use with pools. If we talk about 3000 ppm and then talk about 6000 ppm it seems like a huge difference. The reality is, 3000 ppm is 0.3% and 6000 ppm is 0.6%. One is slightly less than 1/2 of 1% and the other is slightly more than 1/2 of 1%. If you picture where these levels fit on a scale of 1 to 100 you begin to get a grasp of the true reality out there.

There are definitely some benefits as far as comfort goes by adding salt to a pool. The manufacturers decide where to draw the line as far as levels go and they all have heir own reasons for doing that. At the same time, we need to look ourselves in the mirror and decide whether our systems should be used in all situations. Watermaid has been clear from the beginning. Above ground pools present a situation that could lead to corrosion problems. That has NOTHING to do with the fact that Watermaid runs pools at 6000 ppm. It has everything to do with evaporation of ANY salt pool solution. WE do not make units for above ground pools and we do not plan to. There is a lot of money to be made in this market but we do have to live with ourselves.

Mark Manning
Watermaid Canada
www.watermaid.ca
mark@watermaid.ca

[haze_1956]

I keep reading about "Salt in thousands of PPM", or a "Concentrated Salt residue", in the AG pools bottom track due to splash out and evaporation.

But it seems to me that what you will eventually have is, "Solid Salt Crystals", filling the groove in the bottom track.

Or am I mistaken on the assumption?

[waste]

Mark, sorry to have diseminated BS, thanks for setting the record straight. Also, if I misattributed a quote, I'm truely sorry - please, no offence?
(Sean, if I've misquoted you, or have attributed a quote that you didn't make, to you - I hope I haven't offended you and ask your forgiveness) With the old stuff gone, I have to use my memory, unfortunately it's far from perfect - I'll try to be more diligent in noting when I'm 'quoting from memory' from now on. The other problem I see with 'memory quotes' is that I may have missed a rebuttal to what I quote (for instance if Mark had posted a similar one on the old forum), to the posts I was 'quoting' on the old thread - I gotta be more careful.
Haze, it probably won't get to the solid salt crystal point, there's a lot of dirt in those tracks, but that's kind of what you're looking at. Salt doesn't evaporate with the water, which is good, otherwise that essential (for life) mineral would be hard to come by (the only source that I can think of that might not be a result of ocean evaporation would be salt mines - but Idunno). So after GALLONS of salinated water were allowed to pool in one place long enough, you'd get crystals, so the track would have a very high salinity after a while, and as it builds up, it's abilty (and propensity) to rot the metal increases. Ain't it great to have your own chemistry expreiment in your backyard?
Not to wax too philisophical but, for every benifit there is a cost (or potential problem):
If you use trichlor, you get an easy to chlorinate pool, but you have to fight low pH and compensate for high cya
If you use bleach, you don't need so many adjustments for pH, but you have to go out and dose the pool every day
If you get married, you always have someone to share your life and a constant companion, but you can't go out and have a 'one nighter' with the cutie who is 'giving you the eye' in the supermarket checkout line
If you go to an Italian restaurant, you can order great lasagna, but can't get an eggroll with it. etc,etc...