Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 10 of 10

Thread: Suficants, salt, borates and filtering

  1. Back To Top    #1

    In the Industry

    Join Date
    Jul 2009
    Location
    London and France
    Posts
    574

    Suficants, salt, borates and filtering

    Split off of this post. A good introduction to this topic appears lower down. JasonLion

    I believe that most of the scented bleaches also contain ionic surfactants, these reduce the surface tension of the water (make water wetter) and that can flush cryptosporidium oocysts, bacteria and dissolved organic matter out of the filter system.

    More here:
    http://www.drydenaqua.com/afm/applic...ng%20pools.htm

    So as usual just add only what is required

  2. Back To Top    #2
    polyvue's Avatar
    Join Date
    Aug 2009
    Location
    Sacramento, California USA
    Posts
    1,215

    Re: Why unscented bleach

    Teapot, interesting link. Lots of assertions on the page, but they provide references! (too bad they're not internet refs, however )

    Note the ingredients for a scented bleach product (the other scents vary slightly). Also the strength of the product is such that it is not advertised as a disinfectant. At manufacture, the company puts in more lye and less than half of the chlorine used in Regular Clorox (unscented).

    Clorox® Liquid Bleach (Lavender Scent)
    • Water
      Sodium hypochlorite
      Sodium chloride
      Coco-betaine
      Fragrance
      Sodium carbonate
      Sodium hydroxide
      Sodium polyacrylate
      Sodium xylene sulfonate

    Q. Do Clorox® Bleach Clean Linen®, Lavender, Lemon Fresh, and Fresh Meadow® and Clorox® Plus® bleaches disinfect?

    A. Our scented and Clorox® Plus® bleaches are not registered disinfectants. If you need a registered disinfectant, you can purchase Clorox® Regular-Bleach at almost any store that sells laundry products. Make sure that "Disinfects" or "Kills germs" appears on the label.



    • Active ingredients for Clorox scented bleach (MSDS)

    • Sodium hypochlorite 1-5%

      Sodium hydroxide 0.1-1%

    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
    __
    View of spiral galaxy in Ursa Major NGC6217 - Hubble Telescope 2009

  3. Back To Top    #3
    TimS's Avatar
    Join Date
    Sep 2009
    Location
    Central Missouri
    Posts
    214

    Re: Why unscented bleach

    Teapot,

    Great information. Thanks.

    ...these reduce the surface tension of the water (make water wetter)...
    Doesn't salt do the same thing, though? I was under the impression that that was one of the side effects of a water softener. Once the minerals in the water were replaced with the salt, the surface tension was reduced as a side effect, because of the salt. Assuming that my understanding was correct (a very large assumption, I know,) wouldn't we wind up with the same issue in a SWG pool, or by adding borates, for that matter? I could be completely wrong, but that was the way I understand this to work.

    Thanks,
    Tim.
    24' AG Round (vinyl replaced 0909) - 13500 gal - Sand Dollar Filter (150lb) - Dynamo DYNII-N1-1 1HP - Hayward HP380 Heat Pump - TF-100.
    Central Missouri

    Before I speak, I have something important to say.

  4. Back To Top    #4
    TimS's Avatar
    Join Date
    Sep 2009
    Location
    Central Missouri
    Posts
    214

    Suficants, salt, borates and filtering

    This is a spinoff of my "Why unscented bleach" thread in "BBB Method" The discussion started getting a bit involved, so at duraleigh's suggestion, I'm moving that portion here.

    Brief recap:
    Original question was why the recommendation was always "unscented" bleach in particular.

    Here's where it started getting deep:

    Teapot:
    I believe that most of the scented bleaches also contain ionic surfactants, these reduce the surface tension of the water (make water wetter) and that can flush cryptosporidium oocysts, bacteria and dissolved organic matter out of the filter system.

    More here:
    http://www.drydenaqua.com/afm/applicati ... 0pools.htm

    So as usual just add only what is required
    This prompted my next question:

    Doesn't salt do the same thing, though? I was under the impression that that was one of the side effects of a water softener. Once the minerals in the water were replaced with the salt, the surface tension was reduced as a side effect, because of the salt. Assuming that my understanding was correct (a very large assumption, I know,) wouldn't we wind up with the same issue in a SWG pool, or by adding borates, for that matter? I could be completely wrong, but that was the way I understand this to work.

    I'm taking a big risk coming into the deep end with a question like this. I might drown here.

    Thanks,
    Tim.
    24' AG Round (vinyl replaced 0909) - 13500 gal - Sand Dollar Filter (150lb) - Dynamo DYNII-N1-1 1HP - Hayward HP380 Heat Pump - TF-100.
    Central Missouri

    Before I speak, I have something important to say.

  5. Back To Top    #5

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085

    Re: Suficants, salt, borates and filtering

    Tim,

    Salts, such as borates that seem to reduce surface tension, are not the same as surfactants that also more directly interfere with flocculants or coagulants that have things get caught in the filter. On this forum, we generally don't use such latter products to keep our pools clean and clear, but even if we did I don't think salts (including borates) would interfere.

    If you read the Dryden-Aqua article, you will see that it isn't the lower surface tension of the water that is the primary problem, but that surfactants are typically long-chained molecules with a net charge and therefore similar to some of the coagulants that catch smaller particles so they get caught into the filter. If the added surfactant has the opposite charge of the coagulant that is used, then they will tend to combine rather than the coagulant consolidating the other smaller objects (Crypto spores, etc.) that you are trying to get caught in the filter.

    In particular, most of the coagulants are cationic (i.e. have a net positive charge) including Dryden-Aqua's own APF or more common PAC (Poly(Diallyl Dimethyl Ammonium Chloride) or even PolyQuat (yes, it's not just an algaecide, but also a water clarifier -- Poly{oxyethylene (dimethyliminio) Ethylene (dimethyliminio)ethylene dichloride}). These positively charged substances are used because the surface of most cells is negatively charged (even gram positive bacteria have a negative cell surface). So if you add an anionic surfactant, then its negative charges will get attracted to the positive charges of the coagulant and they will combine and filter out, thus removing the beneficial effect of the coagulant.

    Note that nothing I just described in the previous paragraph had to do with surface tension. The fact that surfactants affect surface tension is not the direct problem with regard to interfering with coagulants. Salts won't seriously interfere with the coagulants and even if they did, you (most likely) aren't using coagulants in your pool anyway. You have a residential pool with low bather load where the use of a coagulant is usually not justified. Crypto only comes from another person with diarrhea so your risk is low. Chlorine is used to kill most everything else. The low bather load allows the chlorine to oxidize bather waste and other materials in a reasonable period of time and your filter to remove larger unoxidized materials as well. Commercial/public pools with higher bather loads need more assistance both with oxidation and with coagulation to keep their pools clear and to remove organic precursors as much as possible to minimize disinfection by-products. That is most likely not your situation, especially if you have a reasonable amount of water replacement each year.

    Richard
    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"

  6. Back To Top    #6
    no-mas's Avatar
    Join Date
    Jun 2008
    Location
    FL
    Posts
    405

    Re: Suficants, salt, borates and filtering

    Water softeners don't eaxctly add salt; they replace Ca++ (and other divalent) ions with Na+ ions. Divalent cations like Ca++ and Mg++ will form insoluble salts and compounds (scale, soap scum, etc) much more easily than will sodium ions. That's why water with calcium/magnesium/iron etc feels hard.

    After all, ocean water has much higher sodium content than pool water, but ocean water is certainly not soft. The other dissolved minerals in ocean water make it hard.
    18k gal inground, everbrite finish, 505 sq ft; 1.5 hp two speed whisperflow; rheem 5100ti 100k btu heat pump; 3 sheer descent falls; DE filter; swg (cell out and using trichlor for now)

  7. Back To Top    #7
    TimS's Avatar
    Join Date
    Sep 2009
    Location
    Central Missouri
    Posts
    214

    Re: Suficants, salt, borates and filtering

    Richard,
    So the problem is that the surfactants (hey, I spelled it right this time ) bind with the coagulants thus leaving fewer coagulants available to bind with bacteria and other gunk? Assuming that a pool doesn't have any coagulants in it, (as it normally wouldn't, right?) then the surfactants don't bind with the coagulants (since they're not there,) but instead get captured by the filter media itself, thus leaving less surface area for the filter to collect other gunk, thus resulting in the same basic outcome, (reduced filtering performance.) Is that even close?

    If you read the Dryden-Aqua article,...
    I did that. That doesn't mean that I interpreted it correctly (or even really understood it.)


    no-mas:
    Water softeners don't eaxctly add salt; they replace Ca++ (and other divalent) ions with Na+ ions.
    Well, true. I simplified it a bit.

    After all, ocean water has much higher sodium content than pool water, but ocean water is certainly not soft. The other dissolved minerals in ocean water make it hard.
    True, as you say, there is a lot of stuff in ocean water that isn't in a pool.

    I saw the recommendations to add salt / borates to the pool to make the water "silkier" and combined that with my (erroneous?) belief that one of the effects of water softeners was to actually reduce the surface tension of the water, and thus it was the addition of the sodium ions that did that, thus the advantage to adding salt to the pool was to reduce surface tension. Then misinterpreting what teapot said regarding surfactants came to the conclusion that lower surface tension = reduced filtering. (Wow, was that hard to follow, or what?)

    Wow, I knew I was going to need my waterwings on this foray into the Deep End. [wanders off to enroll in a chemistry class to understand what the heck everybody's saying.]
    24' AG Round (vinyl replaced 0909) - 13500 gal - Sand Dollar Filter (150lb) - Dynamo DYNII-N1-1 1HP - Hayward HP380 Heat Pump - TF-100.
    Central Missouri

    Before I speak, I have something important to say.

  8. Back To Top    #8

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085

    Re: Suficants, salt, borates and filtering

    Tim,

    This stuff gets complicated and confusing so no worries. We all make mistakes or come to incorrect conclusions at times. When I first got into pool water chemistry around 7 years ago, I initially used the molecular weight of hypochlorous acid (HOCl, 52.46 g/mole) for ppm FC & CC units and it took a year before I learned that the actual units used the molecular weight of chlorine gas (Cl2, 70.91 g/mole).

    Quote Originally Posted by TimS
    So the problem is that the surfactants (hey, I spelled it right this time ) bind with the coagulants thus leaving fewer coagulants available to bind with bacteria and other gunk?
    Yes, that is correct, at least when the surfactants are anionic (pool coagulants are almost always cationic). If the surfactants are cationic, then there probably isn't a problem.

    Quote Originally Posted by TimS
    Assuming that a pool doesn't have any coagulants in it, (as it normally wouldn't, right?) then the surfactants don't bind with the coagulants (since they're not there,) but instead get captured by the filter media itself, thus leaving less surface area for the filter to collect other gunk, thus resulting in the same basic outcome, (reduced filtering performance.)
    A pool normally doesn't have coagulants in it unless you intentionally added some, such as a clarifier or even PolyQuat, or accidentally added some, as with swimsuits that have been washed but not thoroughly rinsed. Let's look at PolyQuat specifically since it is a cationic surfactant. The molecular structure of Poly{oxyethylene (Dimethyliminio) Ethylene (Dimethyliminio) Ethylene Dichloride} has each unit of the polymer as follows:

    Code:
           |     |
          -C-   -C-
       | | |+| | |+| |
    -O-C-C-N-C-C-N-C-C-
       | | | | | | | |
          -C-   -C-
           |     |
    with each Nitrogen having a net (+) charge with a chloride ion (Cl-) attached (when in solid form; when dissolved in water the polymer and the chloride separate).
    so its molecular weight is 253.17 for each "poly" unit which has two nitrogen. Each unit is roughly 1 nm in length and there are roughly 16 units in a PolyQuat molecule so that's 16 nm length which is 0.016 microns. So clearly the surfactant molecule isn't going to get caught in an uncharged filter. Sand and cartridge filters are typically uncharged, but DE and other silica-based filter material has a net cationic charge at typical pool pH so will tend to repel the "raw" surfactant. When surfactants combine with anionic (negatively charged) substances including cells in the water, they will tend to form larger clumps and it is these clumps that get caught in the filter. In the case of PolyQuat itself, it kills algae by binding to cell surfaces and interfering with ion transport essentially starving the algae of nutrients.

    Surfactants in detergents tend to be longer polymers around 10 to even 300 times as long as PolyQuat. It's still too small (0.02 to 5 microns) to get directly caught in a filter, but is much better at clarifying the water and in fact specialized pool clarifiers tend to be more like detergent surfactants in size. Those that are based on ammonium compounds, such as PolyQuat, tend to get broken up into pieces since chlorine attacks the nitrogen sites though these pieces are still somewhat effective algaecides. Eventually, they get oxidized or caught and removed from the filter (if attached in clumps to dead algae, for example) which is why one needs to add PolyQuat weekly to replenish.

    So the answer to your question about surfactants clogging the filter is no, not unless there are things to clarify in your pool in which case you want it to get caught in the filter so you can backwash such material.

    Richard
    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"

  9. Back To Top    #9
    TimS's Avatar
    Join Date
    Sep 2009
    Location
    Central Missouri
    Posts
    214

    Re: Suficants, salt, borates and filtering

    Richard,

    Thank you for the explanation. I've reread it several times over the past couple of days. Every time I start to formulate a followup question on the effects of surfactants on filtration and bacteria, et. al. my understanding of it all changes again, and I have to rethink the question.

    I guess the simplest question at this point is, is this the case:
    I believe that most of the scented bleaches also contain ionic surfactants, these reduce the surface tension of the water (make water wetter) and that can flush cryptosporidium oocysts, bacteria and dissolved organic matter out of the filter system.
    It seems somewhat contradictory, but I can come up with (potentially erroneous) arguments either way.

    Tim.
    24' AG Round (vinyl replaced 0909) - 13500 gal - Sand Dollar Filter (150lb) - Dynamo DYNII-N1-1 1HP - Hayward HP380 Heat Pump - TF-100.
    Central Missouri

    Before I speak, I have something important to say.

  10. Back To Top    #10
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,887

    Re: Suficants, salt, borates and filtering

    Surfactants are not normally an issue. There is some risk from trichloramines, but that is fairly minor.They have very little effect on typical pool filters when used with the style of pool care we recommend here. Most of the problems come when they are combined with other pool chemicals that we don't usually recommend using. And most of the things which they might help get through the filter should be destroyed by proper chlorine levels in any case (in the filter or out of it).

    At the same time, there is no reason to add surfactants to the pool in the first place and we do not recommend doing so. Simply don't use scented bleach. Still, if do accidentally use a little scented bleach, the only serious problem is typically going to be the lingering scent.
    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

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •