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Thread: Brand New Hot tub First Fill

  1. Back To Top    #1

    In the Industry

    Join Date
    Oct 2009

    Brand New Hot tub First Fill

    Hello everyone. I have a brand new Strong hot tub, and have many questions. The tub has a capacity of 354galloons. I wanted to know if you are suppose to treat a new hot tub different than that of a properly maintained used one? Like do you need to fill it and then shock, and then drain and refill?

    This is what I did on the tub. I filled the tub from a garden hose after after waiting 2 minutes for any bio film from the hose to
    wash out. I then checked the chemicals.

    PH=8.0(not sure the actually number)

    I then added the Leisure time perfect spa balance. I waited 30 minutes and retested.


    I actually did not test anything else.

    I then went ahead and added sodium bromide and waited 15minutes before I added the Leisure time renew. After I added the renew though, the water became slightly cloudy. Would introducing the renew so soon cause this issue? Also the temperature of the water was at 66 degrees. I do realize that the CH is on the low side. The TA could be at 150ppm.

    I also have a instruction booklet from Spaklear which states I should adjust the calcium to 200ppm before I try to adjust anything else, is that the correct procedure? I always thought you adjust TA, PH, and then CH.

    And lastly, when dealing with hot tubs, should you allow the temp to reach normal operating temps before adjusting anything at all?

    Ok, here is my last question. I tested the water on a pool today, and the ph was 8.0. I then introduced 1gallon of 12% liquid chlorine. I retested 3 hours later and the FC=0 and PH=7.0???? Why did the PH drop? I am using a taylor kit btw. I then tried diluting the pool water sample with hose water to retest the ph. It was 8.0. The pool did have some spots of green algae present.

    Intial Test
    Glad to help with any issues that I can. Send me a pm.

  2. Back To Top    #2

    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Brand New Hot tub First Fill

    You normally do a decontamination procedure when getting either a new or used tub. Even a new tub will have been "wet-tested" and they usually do not completely blow out the lines to dry them so often bacterial biofilms will form. Decontamination is described in this post and more info on hot tub sanitation may be found in How do I use Chlorine in my Spa and How do I use Bromine in my Spa.

    I don't know why the manual says to adjust CH first. As you point out, that shouldn't matter. If the TA is 150 ppm, it will either need to be lower (if you find the pH tends to rise) or you'll need to lower the CH since you don't want to get scaling. Use The Pool Calculator to make sure that the saturation index is below zero. You only need CH to be 120-150 ppm to prevent foaming.

    As for the pool, if you tested the water when the chlorine level was high, then the pH test could have been falsely reading high. The following is from their "Pool & Spa Water Chemistry -- A Testing & Treatment Guide":

    FALSE READINGS: high levels of chlorine (usually >10 ppm) will quickly and completely convert phenol red into another pH indicator (chlorphenol red). This new indicator is a dark purple when the water's pH is above 6.6. Unfortunately, some pool operators mistake the purple color for dark red and think the pool water is very alkaline and wrongly add acid to the pool.

    When a sanitizer level is not extreme, only some of the phenol red may convert to chlorphenol red. However, purple+orange (for example, pH 7.4) = red. This error is more subtle as no purple color is observed and the operator does not suspect that a false high pH reading has been produced. Some operators neutralize the sanitizer first by adding a drop of chlorine neutralizer (i.e. sodium thiosulfate). However, thiosulfate solutions have a high pH and, if heavily used, may cause a false higher sample pH.
    When the FC level went back down, the interference went away and you got back to a more accurate pH reading. Also, addition of chlorinating liquid makes the pH rise and when the FC drops back down the pH goes down as well, but not usually by the amount you saw which is why I suspect interference if the FC was higher than 10 ppm after you added the chlorine. Shocking is not a one-time addition -- you need to keep adding chlorine to achieve a sustained FC shock level of chlorine. That may mean testing every hour and adding more, at least initially, or even more frequently than that depending on how quickly the chlorine is getting consumed.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  3. Back To Top    #3

    Re: Brand New Hot tub First Fill

    I have a few questions...

    Why test FC in a tub that has Sodium Bromide in it already? Shouldn't you be using a bromine test kit since any chlorine added to the tub will give itself up to liberate Bromine from the bromide bank?

    A Gallon of Bleach? Was the Loch Ness Monster in there? Is he vanquished now at least?


  4. Back To Top    #4

    Join Date
    Jan 2009
    Cupertino, CA

    Re: Brand New Hot tub First Fill

    Quote Originally Posted by BCHWB
    I have a few questions...

    Why test FC in a tub that has Sodium Bromide in it already? Shouldn't you be using a bromine test kit since any chlorine added to the tub will give itself up to liberate Bromine from the bromide bank?
    Many chlorine tests will also test bromine, but you use a different scale to read the bromine level.

    Quote Originally Posted by BCHWB
    A Gallon of Bleach? Was the Loch Ness Monster in there? Is he vanquished now at least?

    That was a double-take for me as well, but then that last bit was about a pool, not the hot tub.
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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