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Thread: Is a Salt Water pool same as sea water???

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    Is a Salt Water pool same as sea water???

    Hi All,

    This question could be so dumb perhaps I should not even ask it...here goes nothing...!

    I have a large salt pool and need to drain it for repair, I have the ocean 100ft away so on refilling, can I fill with sea water then get my pool back to "normal" in any way??

    Thanks (for not laughing)

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    TripleB4me's Avatar
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    Re: Is a Salt Water pool same as sea water???

    Salt pools have ~3000 ppm of salt, ocean water is ~35,000 ppm salt.
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    Re: Is a Salt Water pool same as sea water???

    If there's one thing I've learned so far being on this forum, we are all at different stages of development in our "pool knowledge". Therefore there is no such thing as a dumb question. I'm looking forward to reading other's responses to your question, but my understanding is that when someone tells you they have a salwater pool, what they're really meaning is that the pool has a saltwater generator (SWG), which is a device outside the pool (plumbed into your lines) which contains salt, and through a chemical reaction process creates chlorine which is then injected into the poolwater. One of the symptoms of the use of a SWG in a pool is that the water tends to feel different than other non-SWG pools. I think for this reason as well, it makes people think they're actually swimming in a pool filled with saltwater. Not true!

    But a more burning question....with the ocean only 100ft away, what the heck do you need a pool for?!! LOL
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    Re: Is a Salt Water pool same as sea water???

    Thanks Tim, appreciate your support!

    Pool has been "inherited" with my new job, I dont own it, just look after it! I was looking for a way to avoid paying for all the water to refill.
    Guess the water meter will be going into hyperdrive now....

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    JasonLion's Avatar
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    Re: Is a Salt Water pool same as sea water???

    There are "true saltwater" pools and then there are SWG pools. A true saltwater pool is filled with ocean water. These are most common on cruise ships or pools right next to the ocean. A SWG pool has perhaps 1/10th the amount of salt in it that there is in ocean water. An ocean water pool requires using materials that are safe at that salt level. For example the normal copper heat exchanger in a typical pool heater won't work for long with ocean water.
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    Re: Is a Salt Water pool same as sea water???

    you can use sea water you'll just need to dilute it with normal water

    depending on what SWG you have and what materials your pool is made of you could even use sea water

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    Re: Is a Salt Water pool same as sea water???

    Ah Strannik, now we're talking!
    The pool is approx 85,000 gal so obviously I would like to reduce the re-fill costs as much as possible (the house is in a community where the water charges are governed by the "owners")
    Is it possible to part fill with ocean water and top up with fresh to reduce the salt ppm?
    is the a calculator I could use?

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    Re: Is a Salt Water pool same as sea water???

    don't know of a calculator that would do that, usually they calculate how much salt you have to add, not remove

    firstly you'd need to measure the salinity of your sea water. 35 000 is a generic figure, different parts of sea/ocean have different salinity.

    once you know that, the calculation becomes simple.

    salinity/required salinity = 85000/sea water
    sea water = 85000 * required salinity/salinity

    so if your ocean water is 35000 ppm and you want to get it down to 3500 calcs would look like this:

    sea water = 85000 * 3500/35000 = 8500

    meaning you can put in 8500 gallons of sea water and top up the rest with fresh water
    for the simplicity of calcs i'm assuming that fresh water doesn't have any salt content.

    also i would run it through a filter before putting it into a pool

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    Puffin's Avatar
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    Re: Is a Salt Water pool same as sea water???

    I'd be really cautious about using seawater in a pool. The "salt" in seawater isn't just Sodium Chloride (NaCl), there's also magnesium, sulfate, calcium, potassium and some other trace elements. I believe its only like 85-90% NaCl, where pool or water softener salt is 99%+.

    Also consider all of the organics your going to add. Seawater is teaming with life, especially near the coast. You'll have to sanitize and filter it all out as well.

    I'm not saying don't do it, just be aware ocean water is not just salted water. Maybe someone with a better understand of pool chemistry could chime in and mention if the other salts are a problem or not.
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    JasonLion's Avatar
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    Re: Is a Salt Water pool same as sea water???

    Typically the mineral content is not a problem. The organic component can be more troublesome. There are many kinds of algae in ocean water that you don't normally find in pools. Every once it a while one of them can get out of hand. Shocking right after filling should take care of it.
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    Melt In The Sun's Avatar
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    Re: Is a Salt Water pool same as sea water???

    From the sea salt composition here:
    http://en.wikipedia.org/wiki/Sea_salt

    I wouldn't use it. It has a lot of magnesium and sulfate in it, and while I don't know for sure that it would be a problem, one of the TFP commandments is "thou shalt not put stuff in thy pool which thou understandeth not." Well, you get the idea.
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    Re: Is a Salt Water pool same as sea water???

    it won't be a problem in a pool

    keep in mind that it will also be diluted quite significantly to bring salt concentration down to a required one
    a lot of pools in europe that are located near the sea use sea water

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