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Thread: New Frog/Bromine Spa w/ Dichlor shock questions

  1. Back To Top    #1

    Join Date
    Apr 2015
    Greensboro NC

    New Frog/Bromine Spa w/ Dichlor shock questions

    Got a new tub a little over a month ago, 500 gallon four winds 2 pump, frog inline silver mineral w/ bromine cartridge, ozonator too.

    Have questions about shocking the spa. Background below.

    Followed startup instructions from retailer/frog, put in the frog jump start packet (sodium dichloro-s-triazinetrione 33%, 67% other (1.5oz total), and hopped in. At this time the pH and alkalinity were nicely balanced at 7.8 and 120 respectively. I am using Frog brand test strips which measure total chlorine or total bromine, Free chlorine, pH, and total alkalinity.

    First two weeks things were great although the bromine seemed to be on the low side always, likely resulting from insufficient shock on our part after soaking. Went out of town and water got cloudy upon return, and no total Br or Cl, no free Cl, pH and Alka were the same as before. Added some MPS and it took about 3 days to get a bromine reading again (around 1.5ppm). Water was more clear but not like the first fill. After some more soaks, bromine was 0 again, added 2oz dichlor this time. Waited a couple days and back to 1ppm but water is cloudy again (still can see the bottom, just not translucent). Since week 2, the Br and mineral cartridge are set on 6 (highest). Br cartridge replaced at 16th day after first fill. We're about 40 days from our first fill now and I spoke with my dealer about water clarity and low bromine constantly. He concluded the end result is we are not using enough MPS or dichlor on a regular basis. When the tub is safe we soak daily as possible about 1hr at a time, 2 people.

    His recommendation was to add 4oz of dichlor to shock, then another 4oz about 6 to 8 hours later. We did this, and after 2.5 days the water clarity is pretty good, but the total Br/Cl & Free Cl are off the chart on our frog test strips. Total Cl/Br upper limit on the bottle/strip measures 5/10 respectively, and Free Cl maxes out at 5. Our strips were very dark on their color scales so I presume we actually have more total and free than our bottle can read to.

    A few questions:

    1. Is the frog jump start (sodium dichloro-s-triazinetrione) a "bromine bank"? I presume not since it includes "..dichloro..". If not, what is recommended for frog system to get a bromine bank? Sodium bromide I presume? How much for 500gallon fresh fill?

    2. How can you measure your bromine bank vs total bromine on the test strip? I know that Combined Br (CBr) is still an effective sanitizer so Total bromine on the frog strip actually shows Free Br and CBr unlike Chlorine where CCl is pretty ineffective. How is the bromine bank different from Total Br? If you have a bank of 30 to 60ppm, wouldn't that make your bromine levels WAY unsafe, or is it because the bank hasn't reacted with chemical "X" and the test strip doesn't measure Br bank solution until its activated for use?

    3. If I don't have a bromine bank (other than what comes out of frog cartridge), is this why I so frequently read 0 to 0.5 bromine? Maybe this combined with insufficient MPS or dichlor after bathing to oxidize?

    4. What chemical(s) activates the bromine bank to supplement the bromine cartridge.

    5. After adding the total 8oz of dichlor, I presume it is unsafe to enter the tub with total cl/br and free cl readings of 5+/10+ and 5+ respectively? Are these artificial readings?

    6. I took 3oz of hot tub water and 9oz warm tap water and measured the reading to see if I could measure accurately with the frog strips. Total Cl/Br was 3ppm and free cl was 0. This seemed odd to me. pH and Alka largely unchanged. Without dilution I was getting at least 10 TCl and 5Fcl so that would mean combined Cl would be 5 since TCl = FCl + CCl. While the dilution experiment was not scientific by any means, it seems that after 8oz of dichlor that I still have a free chlorine problem. The frog strip indicates that I have 5ppm free Cl and 5ppm CCl although it was beyond the scale so maybe that's equally inaccurate. Does combined chlorine ever go away or do you have to drain the water? I am going to get some strips that read higher Cl. I would like to think that 8oz of dichlor would eliminate any combined chlorine, in theory FCl = TCl at this point. Water doesn't have any foul odor but you can definitely tell chlorine is present. I think that is the CCl that I'm smelling perhaps?

    7. After a shock or superchlorination like i did with the 8oz, when can i tell that I'm actually reading bromine again on the test strips? When FCl hits 0? I suppose I have the same question when adding the maintenance 1oz of dichlor after 1hr of bathing.

    8. Should i use dichlor or MPS for maintenance oxidation of organics? Is there such a thing as having to much MPS to be safe to get in the water? Are there test strips for MPS ppm?

    All in all, the bromine bank is confusing to me and I'm not sure I ever had that to start with. Once I get my Total bromine back in check I think I understand the maintenance of adding 1oz of shock after each use to help oxidize.

    Seems like I should be able to set my Br cartridge to 3 or 4 instead of 6 once bromine bank is available, add some MPS or dichlor after each use, or maybe weekly as hot tub / frog manual says and enjoy more water stability long term with 3 to 4 month drain intervals. Other than after maintenance dichlor addition, my Frog free Cl readings should be zero, correct?

    Thanks for taking time to help a newbie out!
    Greensboro NC
    500 Gal FourWinds Spa
    Frog Mineral/Bromine + Ozonator

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: New Frog/Bromine Spa w/ Dichlor shock questions

    1) No dichlor does not contain any bromine or bromide
    2) There is no easy way to measure the bromine bank
    3) That probably means you aren't using enough. Technically, too little bromine bank means you have a chlorine spa, rather than a bromine spa. Both chlorine and bromine will read on the test, so it appears you are just not using enough.
    4) Chlorine and MPS both reactivate bromine
    5) Usually yes, though the test is not precise enough to tell you for sure.
    6) Tap water has chlorine in it, which will show as bromine on the test, do dilution with tap water won't work
    7) You can't tell if you are measuring chlorine or bromine or some mixture of both, and for the most part it doesn't matter. Both show up when you test for either one.
    8) I would use bleach, basically liquid chlorine. MPS is the most expensive and has no real advantages.
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  3. Back To Top    #3
    Mod Squad pooldv's Avatar
    Join Date
    Aug 2012
    DFW, TX

    Re: New Frog/Bromine Spa w/ Dichlor shock questions

    I don't know the answer to any of those questions. I don't know if you are using bromine for a specific reason or if you are looking for other potential solutions. So, I thought I would share mine.

    I have successfully maintained my hot tub using bleach according to this

    I don't shock ever, just add about 1/8th cup of bleach per bather hour after a soak. Our tub is always clear and ready to go and is used at least 5 times per week. We were hanging out in it for about 3 hours yesterday watching rain and hgtv. It was crystal clear this morning when I got in it. I am very happy with this maintenance process. I didn't change the water for about 10 months either.

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