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Thread: Borax Hardening In Salt Pool

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    bxcrwlly's Avatar
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    Borax Hardening In Salt Pool

    Looking for some ideas/feedback. I use borax in my 11,600 gal. salt pool. Initially I was adding as per TFP guidelines. I began accumulating hardened "blocks" of borax in my pump pot. Wasn't sure what precipitated them to appear. Posted on the forum and suggestion was made to add borax via skimmer in a sock. So I've been doing that thinking that would end my borax chunks. As temps cooled we started using our spa which normally runs with a spillover into the pool. I noticed when we isolated the spa for a soak, the "borax cubes" would appear in the pump pot. My VS pump normally runs at 1800rpm's for circulation and 3000rpm's when running the spa. Appears the additional pressure in the lines is causing these cubes to break-free from somewhere in my system and deposit in the pump pot. I'm wondering if adding the borax with the spa-spillover in operation is causing the borax to deposit somewhere in the spa lines and break free when the spa is activated. Should I refrain from operating the spa-spillover when adding borax?

    I attached a recent photo. The lighter 3 cubes were collected from the previous weekend and the darker 3 cubes, just this morning 2/23 from using the spa this past Saturday night. Sure would like some insight from forum members regarding this unusual situation and to advise on a remedy.

    boraxcubes022315.jpg
    11,600 gallon plaster salt pool & spa, IC20 SWG, IntelliPH, cartridge filter, 2.7HP IntelliFlo Variable Speed Pump, Gas Heater, Easy Touch System w/remote, 8 roof mounted solar panels

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    Re: Borax Hardening In Salt Pool

    How was the Borax originally added? Why do you think that the chunks are Borax? Can you post all of your readings? Are the chunks hard or soft?

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    Re: Borax Hardening In Salt Pool

    You mentioned in this post that it fizzed some when adding acid but not as much as calcium carbonate normally does. Then in this post you used the sock method for dissolving CYA and didn't get the lumps in the pump pot.

    Boric acid is very soluble so it's not that. Cyanuric Acid is less soluble, but still once dissolved it should stay dissolved. With higher calcium levels it's more likely to be calcium carbonate though usually in an SWG pool it shows up as flakes that slough off from the SWG when it reverses polarity.

    Yours is the first report of this type of hardened blocks so there is something different about what is in your pool compared to others. An unusual problem to figure out. A full set of pool water chemistry numbers would help so please post that.
    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
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    Re: Borax Hardening In Salt Pool

    James W - Borax was added via skimmer inside of a sock. See my reply to chem geek below.
    11,600 gallon plaster salt pool & spa, IC20 SWG, IntelliPH, cartridge filter, 2.7HP IntelliFlo Variable Speed Pump, Gas Heater, Easy Touch System w/remote, 8 roof mounted solar panels

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    Re: Borax Hardening In Salt Pool

    chem geek - you are correct, I did notice some "fizzing." It was minor at best. We started using the "sock" method to add via skimmer and didn't notice additional "chunks" in the pump pot; however, this was a period of time where we weren't using the spa. When we started using the spa again, recently, we noticed the "chunks" starting to appear.

    Typically, my pool chemistry is as follows: Free Chlorine = 5.0, PH= 7.5, Salt=3400-3700ppm, Last I checked, my Stabilizer was low at around 40...will be bringing that up to 70 for swim season. Borate levels at last check were around 50ppm using Borate Strips for testing.

    The cubes, when dry, as in the lighter set in pic are extremely light. When first removed from the pump pot they are dense. They have a "soapy" feel to them when wet. When dry they easily crumble with consistency of powdered borax.
    11,600 gallon plaster salt pool & spa, IC20 SWG, IntelliPH, cartridge filter, 2.7HP IntelliFlo Variable Speed Pump, Gas Heater, Easy Touch System w/remote, 8 roof mounted solar panels

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    Re: Borax Hardening In Salt Pool

    Using the spa may have aeration and have the pH rise so that may lead to some precipitation of something that is affected by pH, but it doesn't make sense to be borax. This is a mystery.

    What are your Calcium Hardness (CH) and Total Alkalinity (TA) levels? I wonder what else is in the pool water causing precipitation of these chunks. If you dissolve some chunks in tap water (IF they are able to dissolve), measure the pH and let us know what you find.
    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
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    Re: Borax Hardening In Salt Pool

    This is absolutely fascinating!!!

    As mentioned above, fizzing when in contact with acid suggests Calcium Carbonate, but it is possible that if there are other metals in your water, such as Magnesium, you could be getting something along the lines of Magnesium Carbonate, or some solid solution between Calcium and Magnesium Carbonate. The result is a compound similar to both, but doesn't fizz as much as pure Calcium Carbonate.
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    Re: Borax Hardening In Salt Pool

    In your first post you mention the chunks appear when you isolate the spa; I'm assuming that the spa would then not be spilling over to the pool, but would be recirculating by pulling return water through the spa drain.

    So the obvious path for chunks to get into the pump pot is from the spa drain. Have you pulled up the spa drain grate to see if there's an accumulation of chunks there?
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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    Re: Borax Hardening In Salt Pool

    gtemkin: Yes, when using the spa, it is isolated ie. no spillover. I haven't removed the spa drain as yet. Was awaiting forum feedback before taking that sort of action.
    11,600 gallon plaster salt pool & spa, IC20 SWG, IntelliPH, cartridge filter, 2.7HP IntelliFlo Variable Speed Pump, Gas Heater, Easy Touch System w/remote, 8 roof mounted solar panels

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    Re: Borax Hardening In Salt Pool

    chem geek: Here are some postings regarding past issues with my CH levels.http://www.troublefreepool.com/threa...544#post469544 I had concerns about the high levels. Members such as Richard320 and several others suggested to maintain CSI within range and periodically check CH but not to worry about high numbers. Given that advice, I've been keeping my CSI within standard and haven't been concerned about CH levels. I know the source levels for fill water are around 250ppm. I'll get a recent CH and TA levels test and post results. I know the PH of my source water is 8.0. I'll follow your guidance and try dissolving in tap water and then take a PH reading.
    11,600 gallon plaster salt pool & spa, IC20 SWG, IntelliPH, cartridge filter, 2.7HP IntelliFlo Variable Speed Pump, Gas Heater, Easy Touch System w/remote, 8 roof mounted solar panels

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    Re: Borax Hardening In Salt Pool

    chem geek et. All : Here are two pictures. The first is the container with the dissolved chunk in it. I dissolved it in pool water. My pool water was 7.6 before dissolving the chunk. It dissolved rather easily and created the "milky substance" as pictured.
    IMG_0043.JPG
    The next picture is the PH test of the liquid with the chunk dissolved. As you can see, the PH is off the charts.
    IMG_0044.JPG

    The readings requested on my pool are: ( I also included water temp and salt). When operating the spa the water temp is raised to 100F. I also add 3ou of Hydrogen Peroxide to the spa water to reduce the chlorine concentration which is normally around 5.0 in the pool.

    Water Temp: 70
    Salt: 3550
    CH=620
    TA=50
    PH=7.6

    Hope this info helps to identify the origin and accompanying solution(s) of these chunks.
    11,600 gallon plaster salt pool & spa, IC20 SWG, IntelliPH, cartridge filter, 2.7HP IntelliFlo Variable Speed Pump, Gas Heater, Easy Touch System w/remote, 8 roof mounted solar panels

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    Re: Borax Hardening In Salt Pool

    So it's behaving as if it's a base like carbonate, such as calcium carbonate. That would be consistent with high CH and high pH especially if TA wasn't very low. What is a bit strange is that it didn't fizz more when you added acid to it.

    Now if somehow borax were able to precipitate, it too would raise the pH when dissolved in water (not boric acid, but borax) but I just don't see how borax would precipitate under the dilute conditions in your water (i.e. borax is very soluble in water even if the pH rises).
    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
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    Re: Borax Hardening In Salt Pool

    Quote Originally Posted by bxcrwlly View Post
    chem geek et. All : Here are two pictures. The first is the container with the dissolved chunk in it. I dissolved it in pool water. My pool water was 7.6 before dissolving the chunk. It dissolved rather easily and created the "milky substance" as pictured.
    IMG_0043.JPG
    Are those white things laying on the countertop some of the "chunks"? They're enormous! Would compounds of Calcium and Boron precipitate in chunks without any other evidence of precipitation? Is there any other evidence of precipitation (in a more modest manner), or are the only deposits noticed those chunks?
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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    Re: Borax Hardening In Salt Pool

    If the calcium level is high, it might be calcium borate. I would suggest using boric acid instead of Borax for future additions of borates.

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    Re: Borax Hardening In Salt Pool

    gtemkin: Yes those are the chunks. If you'll scroll to the top of this topic, you can see a pic that clearly depicts them. No other evidence of precipitation other than the chunks.
    11,600 gallon plaster salt pool & spa, IC20 SWG, IntelliPH, cartridge filter, 2.7HP IntelliFlo Variable Speed Pump, Gas Heater, Easy Touch System w/remote, 8 roof mounted solar panels

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    Re: Borax Hardening In Salt Pool

    Quote Originally Posted by JamesW View Post
    If the calcium level is high, it might be calcium borate. I would suggest using boric acid instead of Borax for future additions of borates.
    According to this link, the solubility of calcium borate in water is 0.3 g per 100 cc so 3 grams per liter or 3000 ppm. I suppose at very high CH and pH that it could form but it seems surprising that it stays solid as chunks in a pump basket where the pH isn't expected to remain as high as near the hydrogen gas generation plate in a saltwater chlorine generator. This patent refers to increasing borate concentration to increase precipitation so perhaps you are on to something that it is the addition of Borax to a pool in high CH that forms the precipitate due to the high pH in the local region of the borax dissolving. So, as you suggest, using boric acid could prevent this precipitation.

    Still, I would think that the calcium borate would form where the borax was added creating calcium borate roughly "in place".

    Was the borax added into the skimmer basket and these chunks then formed in the pump basket downstream?
    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
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    Re: Borax Hardening In Salt Pool

    It's definitely a strange reaction. In any case, I think that adding Borax to the skimmer should be avoided from now on.

    Perhaps Borax got concentrated in a low section of plumbing while the pump was on low speed. A spot such as at a 90 going down from the skimmer or up from the ground into the pump. Then when the pump speed was increased, the formed pieces would be flushed through.

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    Re: Borax Hardening In Salt Pool

    chem geek: Yes, the borax was added in a sock placed in the skimmer basket and placed so as not to restrict water return flow. The chunks don't form in the pump pot, rather they are flushed into the pump pot via the return water lines.
    11,600 gallon plaster salt pool & spa, IC20 SWG, IntelliPH, cartridge filter, 2.7HP IntelliFlo Variable Speed Pump, Gas Heater, Easy Touch System w/remote, 8 roof mounted solar panels

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    Re: Borax Hardening In Salt Pool

    I remember a post from someone who tried to use some fine powder form of CYA instead of the common granular product and he discovered it tended to clump into then difficult to dissolve masses. Any possibility this is CYA related instead of a Borax related one? The milky white appearance of the broken up chunk "dissolved" in water looks like very much like a dispersion/suspension of un-dissolved particles (possibly CYA?).
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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    Re: Borax Hardening In Salt Pool

    I would think dissolving some chunks in a container of distilled water and testing for CH, borates and CYA would answer a lot of questions.
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