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Thread: tenacious mustard algae problem - TDS?

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    nuklhed's Avatar
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    tenacious mustard algae problem - TDS?

    Seeking guidance from community. We have very hard water here, TDS in 2-yr-old pool water now 802ppm. Fresh in tap (private well) is 245ppm. Post water-softener (Lithium salt) 297ppm. Somewhere I read that high TDS makes chlorine less effective. Is this correct? FC, TC, CYA, pH consistently all within range, yet I cannot get ahead of mustard algae, much of it clinging to walls and in calm water. Is this more a TDS problem than of chemical balance?
    23,000g IG plaster, slate tile and masonry cascades. Three levels, two pumps: (upper wading 12" dp, with 3.5-ft slate cascade); secondary (double 2-ft waterfall cascades); lower main swimming, two skimmers. New Ultraflex II. Hayward: 3hp pump, 4-cartridge filter. Las Vegas, NV (desert enviro). Water temp: winter avg. 45f, summer avg. 86f. Water service: private well, TDS hard @ 250+ppm but NO Ca+ !! Persistent mustard algae.

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    Richard320's Avatar
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    Re: tenacious mustard algae problem - TDS?

    It is not TDS. Only astronomical CYA levels will make it difficult to clear algae.

    You need to SLAM the pool, and after it has passed the three tests, if there's still mustard algae somewhere, then jack FC up to mustard algae shock level to finish it off.

    If you don't have the proper test kit, don't even try to SLAM until you do
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    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: tenacious mustard algae problem - TDS?

    TDS will almost never be a problem, in fact many people here with SWG pools probably have a TDS of over 5000 and have perfectly clear pools.

    You say everything is within range, but would you mind sharing the exact numbers with us? We really like to see numbers here, kinda our thing
    JD - 28' Round Above Ground Pool, 17,000 Gallons. Dual speed Jacuzzi pump with cartridge filter. Dual speed 1 HP pump, Hayward S210T sand filter
    Pool School - PoolMath - HIGHLY Recommended Test Kits

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    Re: tenacious mustard algae problem - TDS?

    FC, TC, CYA, pH consistently all within range
    Well, not really.

    Algae of any type can only exist in a pool with inadequate chlorine.

    Can you post a full set of test results?

    Then, read "The ABC's of Pool Water Chemistry" up in Pool School

    We'll help you get rid of it but we need to know where you are starting from....Current, valid test results are how we get started.
    Dave S.
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    Re: tenacious mustard algae problem - TDS?

    ICK!!! TDS up to 5000? And it's still a liquid?

    Regrets that I don't HAVE better test numbers because I'm having a hard time parting with $100 of my hard-earned for a proper test kit (Taylor 2006C?) - I'm still using test strips.

    But I'm VERY grateful for the feedback however and promise to start giving good numbers soon as I can.

    At some point also I will want to start a new thread into means of removing/reducing TDS by some high-tech process - maybe with view to product development for the residential pool industry. So far, nobody has stepped into that space even though effective/efficient processes do exist in large scale water-treatment plants. Maybe others have tried but the technology just isn't feasible at single-user scale.

    All my concerns above, by the way, in a lunatic pursuit of reducing lime-deposit at waterline. Show me an easier way to cope with that and I'll chase it!
    23,000g IG plaster, slate tile and masonry cascades. Three levels, two pumps: (upper wading 12" dp, with 3.5-ft slate cascade); secondary (double 2-ft waterfall cascades); lower main swimming, two skimmers. New Ultraflex II. Hayward: 3hp pump, 4-cartridge filter. Las Vegas, NV (desert enviro). Water temp: winter avg. 45f, summer avg. 86f. Water service: private well, TDS hard @ 250+ppm but NO Ca+ !! Persistent mustard algae.

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    Re: tenacious mustard algae problem - TDS?

    Sea water has 40,000 ppm of TDS and it is very much liquid. You can reduce your TDS through reverse osmosis, available for pools in a lot of desert communities, but your problems are in not related to having dissolved solids in your pool, but what those dissolved solids are. To determine what those are and which ones are out of whack you need a good test kit. A good test kit is also the answer to your mustard algae problem and can help you control your lime situation.
    JD - 28' Round Above Ground Pool, 17,000 Gallons. Dual speed Jacuzzi pump with cartridge filter. Dual speed 1 HP pump, Hayward S210T sand filter
    Pool School - PoolMath - HIGHLY Recommended Test Kits

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    Re: tenacious mustard algae problem - TDS?

    If you are really serious about taking control of your water quality, you need a good test kit. Strips are just not adequate. The TF-100 or the K-2006 would be a good choice.

    http://tftestkits.net/Test-Kits-c4/

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    Re: tenacious mustard algae problem - TDS?

    Quote Originally Posted by nuklhed
    All my concerns above, by the way, in a lunatic pursuit of reducing lime-deposit at waterline. Show me an easier way to cope with that and I'll chase it!
    The lime deposit has more to do with the combination of pH, TA and CH than with TDS. So when you are talking about water replacement or reverse osmosis, you are really focussing on reducing your CH level, but since we don't know what that level is, we really don't know if that is the problem.

    Get yourself one of the two recommended test kits. Then post your numbers and we'll help you out.

    By the way, when pool water is saturated with calcium carbonate to protect plaster, it will often leave a thin layer of white on tile from the splash/evaporation cycle and that is normal and disappears when you rub it or get it wet. Is that what you are seeing or are you seeing much more serious scale that does not rub off or disappear and is thicker?
    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"

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    Re: tenacious mustard algae problem - TDS?

    Thanks BIG for this depth of inquiry. This gives me chance to mention something nobody even in the shops is prepared to speak about.
    Clearly I have a major imbalance problem because the liming at waterline is quite thick and dense. Splash zones even get to a thickness where it will flake off in 1" chips.
    But that's not what I'm responding to here -- when I get a decent test kit we will zero in on the real problem and fix it.
    Here's the real deal: I tackled this problem on a small area with a bucket of half-diluted MA and a stiff-bristle scrub brush, and the majority of the white deposit did come off with diligence. BUT - there was another remainder left behind that did not react with the acid, even at full strength. It's a light grayish color and clings extremely hard so only a pumice stone can scrape it away. It's just like a thin layer of reg'lar portland cement, and sticks just as hard. I have noticed this many times before but sales guys in the shops tell me they have never seen it. Hrumph... either they don't have anywhere near the experience they claim, or they didn't look very closely at their own workmanship. This tough hard gray deposit is common and >> I think it's a salt of magnesium <<. Does anyone know what this grayish hard deposit is? It may be a chloride or chlorate of magnesium since it does not react with HCl.
    BTW - there's so much white deposit on my pool by now (18 months of negligence) that I will simply wait until end of swim season then drain and sandblast to restore finishes. Until then, practice with testing and feedback from TFP community will educate me how to sustain proper water balance and prevent this problem from happening again.
    MANY thanks to all respondents, it's invaluable to have so much expertise volunteering.

    -- da nuklhed
    23,000g IG plaster, slate tile and masonry cascades. Three levels, two pumps: (upper wading 12" dp, with 3.5-ft slate cascade); secondary (double 2-ft waterfall cascades); lower main swimming, two skimmers. New Ultraflex II. Hayward: 3hp pump, 4-cartridge filter. Las Vegas, NV (desert enviro). Water temp: winter avg. 45f, summer avg. 86f. Water service: private well, TDS hard @ 250+ppm but NO Ca+ !! Persistent mustard algae.

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    Re: tenacious mustard algae problem - TDS?

    In addition to calcium carbonate, you could also get other types of scale, such as calcium phosphate and/or calcium sulfate.

    I would suspect that the scale that did not react with the acid is probably calcium sulfate. Member onBalance reports seeing calcium sulfate scale in Las Vegas.

    http://www.anotherperfectpoolnews.com/w ... update.pdf

    If you can post a full set of readings from your pool water, that would help. Readings should include:

    FC, CC, pH, Total Alkalinity, Calcium Hardness, Cyanuric acid, Temperature, Phosphates, Sulfates, Salt (measured using a chloride titration test, such as the Taylor K-1766).

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    Re: tenacious mustard algae problem - TDS?

    Well, without getting into "stoichiometry" or electromotive force and all that rot [god forbid the brain damage], I'm left wondering why HCl would attack a carbonate but not a sulfate of Ca+. I know our soils here are loaded with gypsum, which Wiki tells me is Calcium Sulfate CaSO4 - and which I presumed was the bulk of the white deposit on my tile simply because of its dominant presence. But maybe it's carbonate because it fizzed up so well when removing. It's also likely we have much epsom salt, Magnesium sulfate in our soils, but more must be learned.
    At risk of diverting attention down darker alleyways, this thread gives me chance to raise subject of filling a pool with >> softened << water. Has anyone actually done this? I speak about it occasionally at the pool stores (NPS), and once the sales guys get over their shock, they quickly begin avoiding me like a raving lunatic. Honest boys, I'm not dangerous.... I just like to think out of the box.!!
    So, I ask Community for any feedback on swimming pools filled with softened water.
    Just recently, thanks to a TDS meter, I just discovered that my softened household water actually has a higher TDS reading than the source well. That it doesn't leave spots then, and makes for better cleaning, suggests its salts (Lithium in my case) are far more soluble and therefore less likely to create white deposit at waterline and splash zones. It might make for a superior swimming experience too, plus delay the cost of drain and refill (about $700 here in Vegas) which most locals do every couple years since our utility water is very hard 290ppm. But I cannot find any definitive resource to report on the idea.
    BTW - I have spoken with many people about RO and it just isn't feasible in any case, much less with a home on well and septic tank. FYI.
    23,000g IG plaster, slate tile and masonry cascades. Three levels, two pumps: (upper wading 12" dp, with 3.5-ft slate cascade); secondary (double 2-ft waterfall cascades); lower main swimming, two skimmers. New Ultraflex II. Hayward: 3hp pump, 4-cartridge filter. Las Vegas, NV (desert enviro). Water temp: winter avg. 45f, summer avg. 86f. Water service: private well, TDS hard @ 250+ppm but NO Ca+ !! Persistent mustard algae.

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    Re: tenacious mustard algae problem - TDS?

    Softened water doesn't change the TDS by much -- only due to the units of measurements of weight and the method of TDS measurement (conductivity vs. evaporation/weighing). The reason is that a water softener simply exchanges one type of ion, such as calcium or magnesium, with another type of ion, such as two sodium (since calcium and magnesium are doubly charged). So the TDS from a number of ions (charged atoms) perspective is doubled while from a conductivity perspective it is a function of the relative conductivity of these ions and roughly speaking sodium (5.011) is half as conductive as calcium (11.900) and magnesium (10.612) but there are twice as many sodium so it's close to a wash (theoretically, a small drop TDS in terms of conductivity of 6%-16%). A water softener will certainly make your water less likely to form calcium carbonate scale.

    The carbonates are generally easier to remove with acid because the acid (hydrogen ion) combines with the carbonate to form carbonic acid that then forms carbon dioxide and water so the end result is quite a bit more thermodynamically favorable and also doesn't build up locally in concentration as much due to gas bubbles that rapidly move away from the site of formation. With sulfate, it simply goes from being bound to calcium to being a free ion so the hydrogen ion doesn't participate in this to form a new product -- that is, it's really no different than water kicking out the sulfate ion. The sulfate is fairly tightly bound and when it is knocked out it tends to pop back in since diffusion is so slow.
    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"

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    Re: tenacious mustard algae problem - TDS?

    First, apology to entire community for humiliating and stoopid reference to lithium salts. Gave myself a dope-slap on your behalf, the real chemistry is potassium salt, as chloride, in water softening.
    I hope all readers could infer what was intended. Please reset your mental database to the correct info.
    Concept is to reduce NaCl in diet, for health.
    The stuff is not cheap, KCl costs $20/bag vs. $5/bag for NaCl. Our softener (Watts Premier - CostCo, $400) is dialed back to bare minimum and we're still using a bag per month. At factory default setting it was using a bag ever two weeks.
    23,000g IG plaster, slate tile and masonry cascades. Three levels, two pumps: (upper wading 12" dp, with 3.5-ft slate cascade); secondary (double 2-ft waterfall cascades); lower main swimming, two skimmers. New Ultraflex II. Hayward: 3hp pump, 4-cartridge filter. Las Vegas, NV (desert enviro). Water temp: winter avg. 45f, summer avg. 86f. Water service: private well, TDS hard @ 250+ppm but NO Ca+ !! Persistent mustard algae.

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