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Thread: chemical interactions?

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    Join Date
    Nov 2016
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    chemical interactions?

    I need to add borax to balance PH, baking soda for TA, chlorine, salt, boric acid, and calcium choride. Are there some that can be added simultaneously and some that have to be kept separated?

    The instructions for the calcium say to avoid adding until the day after PH adjustments, but what about the others?

    And I think that the boric acid should be last due to its buffering power - right?
    30k IG vinyl w steps , Pentair SuperFlo 342001 pump, StaRite Cristal-Flo sand filter T-240-BP1
    Hayward Goldline AQR15 SWG, Dolphin Premium (aka S300i) Robot
    Borates & TF100 test kit
    200 gal hot tub (that I completely rebuilt)

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    Re: chemical interactions?

    If you increase TA, your pH will come up and you won't need to raise pH.

    You really don't need calcium in a vinyl pool. What's your current calcium hardness and what's your target?

    Salt is pretty neutral and does not react with many things.

    In any case, always give at least 30 minutes between additions. Brush well to mix.

    What are all of your readings and target levels?
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    Join Date
    Nov 2016
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    Helena, AL
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    Re: chemical interactions?

    Current readings
    CYA = 35
    FC = 2.5 (I added a jug of bleach already and brought it up to 6.5)
    TA = 50
    CH = 40
    PH = 7.2
    Current Salt = <200
    Current Borate = 0

    Pool Volume
    Based on rough measurements, I calculated the volume to be ~30k gallons. However, the addition of bleach per Pool Math values for 30k gallons has increased the resulting FC by a greater number than it says it should. By using the pool volume as the unknown variable and the volume of bleach and resulting FC increase, Pool Math is telling me that the pool volume is 20k and 22k gallons on two separate trials. I added 6 bags of solar salt and will do the same reverse calculation to see if it also indicates ~20-25k gallons.

    TA and PH

    I want to add the boric acid, which will lower my PH by ~0.3. I was going to bring TA up to 65 (I've read that the target should be between 60-90, but you should target the low end when adding Borates - so I chose 65. So I need 77 oz. of baking soda (assuming the 22k gallons described above). According to Pool Math, this will only raise my PH by 0.03... which is insufficient for the low PH and the additional drop that will occur when the boric acid is added... so I need to use the borax to help jump the PH without bringing the TA too high.

    CH
    I've read a variety of advice regarding recommended CH levels. I think Pool School says anything <300... but strewn throughout other postings are various other recommendations on level (even for vinyl pools). Based on everything that I read yesterday, I was planning to target 200.



    My Question:
    So, the main thing I'm trying to figure out is... are there chemical interactions that require things to be added in a specific order or separated by a certain amount of time? This is not really just a question for this addition, but for future adjustments both in my hot tub and in my pool.

    For instance, last night when I got out of the hot tub and tested levels, it also needed PH and TA to increase along with a splash of bleach. I'm not sure if I can add Borax, Baking Soda, and Bleach all simultaneously or not. Doing so would save some time, but will it cause a problem? So last night I added the bleach, waited a while, then added the borax and baking soda.
    30k IG vinyl w steps , Pentair SuperFlo 342001 pump, StaRite Cristal-Flo sand filter T-240-BP1
    Hayward Goldline AQR15 SWG, Dolphin Premium (aka S300i) Robot
    Borates & TF100 test kit
    200 gal hot tub (that I completely rebuilt)

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    Mod Squad pooldv's Avatar
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    Re: chemical interactions?

    The answer is yes, you can add them one after the other with the pump running. I usually move to the other side of the pool when adding bleach and muriatic acid because those two shouldn't be mixed together at full strength. So, I pour bleach in front of one return and the acid in front of a different return on the other side of the pool.

    There is a relationship between pH and TA. The higher TA goes the more it will push up pH over time.

    CH in a vinyl pool should be a minimum of 125 ppm. This is debated somewhat, some say 250, especially if you have a heater. Anywhere from 125 to 300 ppm is fine and there is no downside with having 250 or 300 vs 125.
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    kcindc's Avatar
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    Re: chemical interactions?

    Your TA is at the bottom end of the recommended level, so I wouldn't adjust your TA unless you are battling your PH. Each pool is different as to what TA level works best.
    Karen
    33K IG w spa plaster, Pentair 1HP Whisperflo, DE Filter, SWG CircuPool RJ-60, Dolphin Triton Plus, Raypak Dig 336K BTU, TF-100.
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