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Thread: Dead Sea salts in hot tub

  1. Back To Top    #21

    Re: Dead Sea salts in hot tub

    Quote Originally Posted by jza1736 View Post
    Even more hot tub 1450ppm
    Regular ocean about 50,000ppm
    Dead sea is almost 500,000ppm

    But good luck on your science experiment
    The ocean is about 35,000 ppm and the dead sea is not more than 350,000 ppm, which basically is close to full saturation.
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  2. Back To Top    #22

    Join Date
    Oct 2018
    Location
    Calgary/Alberta
    Posts
    49

    Re: Dead Sea salts in hot tub

    Here's what I found on Wikipedia about Dead Sea chemistry:

    "These results show that the composition of the salt, as anhydrous chlorides on a weight percentage basis, was calcium chloride (CaCl2) 14.4%, potassium chloride (KCl) 4.4%, magnesium chloride (MgCl2) 50.8% and sodium chloride (NaCl) 30.4%. In comparison, the salt in the water of most oceans and seas is approximately 85% sodium chloride. The concentration of sulfate ions (SO42−) is very low, and the concentration of bromide ions (Br−) is the highest of all waters on Earth."

    So it's mostly just a mix of chlorides of sodium, magnesium, calcium with a less significant amount of potassium chloride and by the looks of it bromides of at least some of these ions too but the article doesn't really say what the bromide levels are just that they're higher than in any other natural waters. I'm a bit surprised to see sulphates are so low. I expected to see some sulphates of calcium, magnesium and sodium in there as well but I guess not so much. If the dead sea salt is expensive you could sort of mimic it by using a mixture of sodium chloride with de-icing salt or dust control mixture which are usually either calcium chloride or a mixture of calcium and magnesium chlorides. You wouldn't likely get any or much KCl but that's just a minor component of dead sea salt anyways so it probably wouldn't make much difference.

    I don't lnow much about salt water systems. What kind of concentrations of chlorides do you run in them? Personally, I wouldn't want to use those systems if the [Cl-] is very high. Chlorides are very mobile and persistant in the environment and contaminate groundwater very easily.
    I can take ANYTHING apart

    1995 Hot Springs Grandee
    500 US gallons (1,893 L) 104 F (40 C)
    Fibreglass construction

  3. Back To Top    #23

    Join Date
    Oct 2017
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    Roscoe, IL
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    221

    Re: Dead Sea salts in hot tub

    Quote Originally Posted by DangerBoy View Post
    I don't lnow much about salt water systems. What kind of concentrations of chlorides do you run in them? Personally, I wouldn't want to use those systems if the [Cl-] is very high. Chlorides are very mobile and persistant in the environment and contaminate groundwater very easily.
    Less than a non-salt water spa/pool. Surprising, huh?

    Say you need 3000 ppm salt to run a SWCG. You add the salt upfront. The SWCG then continually will "reactivate" the chloride ions into hypochlorous acid by creating chlorine gas from the chloride ions which dissolves into the water and becomes hypochlorous acid which breaks down into chloride ions when it does it's oxidizing thing which are turned into chlorine gas by the SWCG and so on. You're recycling your chloride ions.

    Adding liquid chlorine (sodium hypochlorite) is similar, it will become hypochlorous acid, then break down into chloride ions after it oxidizes waste. But these aren't recycled, so you just keep adding more chloride ions (and sodium Na+) ions the more bleach you add. Say you have a 400 gallon spa. Each 10 ppm of FC added adds 17 ppm salt (according to PoolMath). Add 176 ppm FC and you've added the same amount of salt as the 3000 ppm of salt you added to the SWCG spa. If you need to add 20 ppm FC per week, that's 9 weeks and you've added more salt overall than you would in a SWCG. Given you go 3-4 months typically between spa water changes in this example you've added twice as much salt in the non-SWCG spa than you would in the SWCG. For a pool that goes years between water changes this probably gets even more extreme in favor of the SWCG, if adding salt (chlorides) to the environment is your concern. But bottom line the SWCG will always add way less chloride overall the the spa/pool/environment.

    If you want to look at the actual chemistry going on here, nobody can explain it better than chem geek: Pool Water Chemistry

    P.S. Either way it pales in comparison to the amount of chlorides a water softener will run down the drain. At my old house I think I was running 40-80 lbs of salt a month down the drain. Terrible, so terrible. I mean a 400 gallon spa only needs 10 lbs of salt to get it to 3000 ppm and then you can run it with a SWCG for 4 months! I really want a European style dishwater with a built-in water softener (can't seem to get those in the US) so I can get clean dishes but don't have to throw nearly so much salt down the drain. I now currently rent with no softener, gave up on dishwasher because it's so terrible at cleaning between being a cheap model and hard water and I wash dishes by hand. Once I buy I will either see if a dishwasher with built-in softener is available in the US yet, or get one that works off cold water and run a "RV-style" mini water softener to the dishwater only.
    Hot tub: Indoor Intex 28409E "Six Person" inflatable. 290 gallons. Taylor K-2006 test kit with Taylor 9265 Speedstir and TFT CYA test. Using dichlor/bleach/borax/muriatic acid.

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