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Thread: Quantity of bromide salt required

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    Quantity of bromide salt required

    I have an in-ground freeform 1200 gallon hot tub with a Pebbletec finish which really looks more like a small plunge pool. Upon instal a year ago, the pool builder included a Genesis Bromine Generator which, unfortunately, has not been able to produce enough bromine to keep the tub sanitized. We believe the generator does not work properly as it is designed for much smaller hot tubs that are covered, whereas my tub is in the open air and of larger capacity than conventional spas. As a result, I also have a floater with bromide tablets as well. I follow the BBB method and add Clorox every other day, and shock with Clorox once a week. I also have 1 inch bromine tablets in a floater.

    My question is regarding the amount of bromide salt required upon drain and refill of my hot tub. The instructions from the Genesis Bromine Generator manufacturer states 1 lb. of Tru Blu (which I presume is bromide salt) per 100 gallons of water. This would therefore equal 12 lbs. of Tru Blu for my hot tub. However, the instructions on the side of the bucket in which the bromine 1 inch tablets are contained states 1/2 ounce of bromide salt per 100 gallons at start up or refill. Obviously there is a huge difference between 1 pound and half an ounce!

    I am due to empty and refill my hot tub and will need to reinstate a bromide salt content for bromine reserve. Can someone please tell me whether the Tru Blu (1 lb) or the bromine tablet (1/2 oz) per 100 gallons is correct? The Tru Blu product is very expensive and I don't want to purchase more than I need. Or should I just forget the Genesis altogether and simply go with 1/2 oz per 100 gallons which would be 12 ounces total at refill, and then Clorox and 1 inch tablets forever more?

    Thanks so much for this fantastic forum.

    Sandi in Dallas, Texas

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    JasonLion's Avatar
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    Re: Quantity of bromide salt required

    If you are using the Genesis Bromine Generator, you have to have an incredibly high bromide level for everything to work correctly. The instructions I saw at their web site said 2 lbs per 100 gallons. If you are dosing manually a much much lower bromide level will be fine, something around 1/2 oz per 100 gallons.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Quantity of bromide salt required

    Thanks, Jason. As the Genesis is barely producing bromine (due to spa being uncovered and 1200 gallons) I think I'm just going to turn it off and add the 1/2 oz per 100 gallons of sodium bromide that goes with the 1 inch bromine tablets.

    Final question -- will just a floater with the inch bromine tablets, plus adding Clorox every other day (and shocking with Clorox once a week) be adequate for sanitization?

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    JasonLion's Avatar
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    Re: Quantity of bromide salt required

    Yes, that should work.

    If you haven't already you might want to read how to use bromine in your pool/spa.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Quantity of bromide salt required

    Thanks again, Jason. And yes, I have read (and re-read) the "How to use bromine in your pool/spa" and plan to follow the 3-step process after turning off the Genesis (which, as it turns out, is only suitable for spas up to 500 gallons!).

    I have another question though. Do you think the excessively high bromide salt requirement that goes with the Genesis might contribute to what seems to be a never-endingly high pH? I find it very difficult to keep the pH around 7.6 ish and every other day it has crept up to over 8.0 and the test water is very dark pink. I feel like I'm continually adding muriatic. I do have a waterfall which I have turned down to a dribble, and even sometimes turn off completely but it doesn't seem to help my pH doing either of those. I also notice the pH battle is worse in the Texas summer (today is going to be 105 degrees).

    I'm wondering if emptying the spa-ool, refilling, re-balancing and going with the 3-step process where I will only add back 1/2 oz bromide salt per 100 gallons might help keep my pH more steady. Any thoughts on this please?

    Thanks
    Sandi in Dallas

    PS I think I've figured out how to include a photo of my spa-ool so you have a better "picture" of my situation.
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    JasonLion's Avatar
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    Re: Quantity of bromide salt required

    You want to have a very low TA in a spa. The spa jets provide lots and lots of aeration, which tends to rapidly raise the PH unless TA is quite low. What is your TA currently?
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    Re: Quantity of bromide salt required

    I tested TA and pH about two hours ago. TA was 70 and pH was 8.0+. I added 5 oz. of baking soda to raise the TA to about 100 as I need to add muriatic to bring down the pH, which of course also brings down the TA. I haven't added the muriatic as yet but planned to do so shortly.

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    Re: Quantity of bromide salt required

    Oh, and some additional information ..... we don't turn the spa heater on at all after about April here in Texas, and only turn on the jets maybe one night a week for 30 minutes or so. In these warm summer months we really treat it more like a small pool to cool off in, rather than as a spa like we do in winter.

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    JasonLion's Avatar
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    Re: Quantity of bromide salt required

    Stop raising the TA. That is what is causing the PH to rise. Let the TA come down to around 60, perhaps lower if you add borates, and the PH will be much more stable (though perhaps not perfect).
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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