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Thread: Good chemistry but still excessive foam when venturi valves

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    Good chemistry but still excessive foam when venturi valves

    Happy new year everyone. First off, I've searched and read a good number of threads on "foam issues" already, but haven't found any answers to my particular situation.

    My hot tub (~450 gal, 3 step bromine) has been acting funny on me all of a sudden. It hasn't been used much lately and I did inadvertently let the sanitizer get down to almost 0 for a day or two a few weeks ago, but I've been shocking and keeping an eye on pH, TA, and so on since then.
    All the chems are good now and overnight sanitizer loss is minimal (I took pucks out while shocking and doing all this testing), but when I turn the jets on high and open the venturi valves, the water almost instantly begins foaming significantly. The entire water surface will be under 4-6 inches of the fluffy white stuff within 10 minutes. The foam doesn't seem slimy or dirty, but it's there and I don't like it.
    Conversely, I can put the jets on high with the venturi valves closed and not have any foam issues at all.

    Can anyone offer any suggestions?
    Wes
    1) In-Ground pool with vinyl liner
    - ~25,000 gallons
    - Sand Filter
    - 1 HP pump
    - BBB method working perfectly since 2010
    2) Four Winds Honolulu Spa
    - ~450 gallons
    - 3 step bromine

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    Mod Squad jblizzle's Avatar
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    Re: Good chemistry but still excessive foam when venturi val

    What is your CH level? I think I have read that if too low it can result in more foaming.

    Although 4-6"is a LOT of foam.
    Jason, TFP Moderator
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    Richard320's Avatar
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    Re: Good chemistry but still excessive foam when venturi val

    Assuming someone hasn't been jumping in the hot tub all slathered up with lotions, foam is either low CH or algaecide.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Good chemistry but still excessive foam when venturi val

    Thanks guys. I definitely haven't put any algae code in the tub, and bather load has been next to nothing so I don't think it's lotions. I haven't checked the CH though, and I obviously need to do that. The 2 years or so I've owned this tub, I don't think I've ever checked CH. I knew it was important for my pool, but thought it was inconsequential for hot tubs for some reason. Does CH generally dissipate over time in hot tubs? I ask because the water I put in the tub 6 months or so ago would have been right in the target CH range (I know this from my pool water testing).
    Wes
    1) In-Ground pool with vinyl liner
    - ~25,000 gallons
    - Sand Filter
    - 1 HP pump
    - BBB method working perfectly since 2010
    2) Four Winds Honolulu Spa
    - ~450 gallons
    - 3 step bromine

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    Richard320's Avatar
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    San Dimas, CA (LA County)
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    18,768

    Re: Good chemistry but still excessive foam when venturi val

    Quote Originally Posted by wes8398
    Thanks guys. I definitely haven't put any algae code in the tub, and bather load has been next to nothing so I don't think it's lotions. I haven't checked the CH though, and I obviously need to do that. The 2 years or so I've owned this tub, I don't think I've ever checked CH. I knew it was important for my pool, but thought it was inconsequential for hot tubs for some reason. Does CH generally dissipate over time in hot tubs? I ask because the water I put in the tub 6 months or so ago would have been right in the target CH range (I know this from my pool water testing).
    CH doesn't disappear, but it can stick to the walls as scale. More likely, rain or snow have diluted things. The only way to know for sure is to test. Post all the results. "All the chems are good now" in your initial post really don't tell us anything.

    There aren't any teenagers about are there? Nobody thought Mr. Bubble would be fun? Don't expect them to admit it, by the way.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Good chemistry but still excessive foam when venturi val

    Thanks again for the reply. To clarify, I'm in south-western Ontario, Canada and the tub is outdoors and always covered. It's not exposed to snow/rain/elements unless we're in it....which is often maybe only once a week or so. No kids, no teens. Just me and my wife.

    Tested CH just now and the test water went clear (very very light blue tint maybe) at 20 drops, or 200ppm by the TF-100. I added a few more drops to try to make it turn more blue, but that didn't seem to change anything. So suffice to say I'm sitting around that mark.

    As for "all the other chems are good", I was just trying to save posting numbers that've worked for me all along and are within the parameters suggested by Pool School and "the pool calculator". pH is ~7.5, TA is ~70, FC is ~20ppm (using bromine, so free bromine is ~10ppm...still coming down from last shock), CC is less than 1. I'm not sure about borates as I don't have a test for that. But I've added small bits of Borax here and there when dealing with TA/pH issues in the past, so there would be *some* borates present.

    Do any of these numbers look indicative of anything?
    Wes
    1) In-Ground pool with vinyl liner
    - ~25,000 gallons
    - Sand Filter
    - 1 HP pump
    - BBB method working perfectly since 2010
    2) Four Winds Honolulu Spa
    - ~450 gallons
    - 3 step bromine

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    Richard320's Avatar
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    Re: Good chemistry but still excessive foam when venturi val

    Quote Originally Posted by wes8398
    I'm not sure about borates as I don't have a test for that. But I've added small bits of Borax here and there when dealing with TA/pH issues in the past, so there would be *some* borates present.

    Do any of these numbers look indicative of anything?
    Hmmm...any chance you picked up Boraxo hand soap thinking it was borax or Arm & Hammer detergent by mistake, thinking it was baking soda?


    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Good chemistry but still excessive foam when venturi val

    LOL No, fortunately there is no chance I did that!

    Upon further consideration, this has got me questioning the dollar store off-brand baking soda that I recently used a few tablespoons of when my pH had dipped a bit. Wonder if it's an inferior baking soda..? Or even the wrong product or package...? Hmm....
    Wes
    1) In-Ground pool with vinyl liner
    - ~25,000 gallons
    - Sand Filter
    - 1 HP pump
    - BBB method working perfectly since 2010
    2) Four Winds Honolulu Spa
    - ~450 gallons
    - 3 step bromine

  9. Back To Top    #9

    Re: Good chemistry but still excessive foam when venturi val

    Well, opened up the tub and just let it fly with all the jets on high and all the venturi valves wide open. She foamed up a LOT again. Soapy foam again too. I'm 99% convinced that the dollar store "baking soda" I used a few weeks ago is what's caused this issue. I literally used a shovel to scoop out all the foam, then let it run until the suds calmed down. All the chems are still in perfect ranges, and the foaming seems to be over now that I've let it run it's course..... here's hoping.
    Wes
    1) In-Ground pool with vinyl liner
    - ~25,000 gallons
    - Sand Filter
    - 1 HP pump
    - BBB method working perfectly since 2010
    2) Four Winds Honolulu Spa
    - ~450 gallons
    - 3 step bromine

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