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Thread: Pool Fill Water Quality

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    Pool Fill Water Quality

    I have 4 options for water filling. My house supply is from rainwater tanks with water collected from the roofs of my house etc.
    1. Trucked in: expensive. The water is treated (quite heavily from the smell of it). This water is the supply for the nearest town.
    2. I have a large tank which isnt connected to the house and I dont use so the water in there is probably at least 5 years old.
    The tank is leaking a fair bit so I guess it must be quite rusty inside.
    3. As the pool will be finished just before winter, I could empty in most of the water from the house tanks, as they will soon fill up again (and then some) from the winter rains. These tanks probably have some rust inside.
    4. I have a groundwater soak. This is quite saline. The ground here is pure sand but the water will have percolated down from the hills behind where the soil
    in some places (perhaps not immediately behind, I am not sure) is a deep red from all of the iron. I was going to use this water to top up in summer. The SWG has no upper limit for salinity: it can handle sea water according to the manufacturer.

    Numbers 2,3 and 4 aren't enough to fill the pool on their own.

    Should I be concerned about the iron and or rust components in the water? Are there any other issues I should be concerned with.
    11k gallon IG Ferrocement , Onga (Pentair) SF750 1hp pump, Onga Pantera MK11 PCF200sqft Cartridge Filter, Watermaid WM40-QT300 SWG, Spa Electrics GK7 LED

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    JasonLion's Avatar
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    Re: Pool Fill Water Quality

    None of those are ideal. you don't want any significant amount of iron in the pool. Avoid rust if you possibly can. Some slat is alright, but you don't want salt going over 5000. If you call it quite saline, it is probably too much.

    I suggest getting the iron level in your house water tested to see if it is low enough (0.3 or lower).
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Pool Fill Water Quality

    What are the issues with too much iron?
    The manufacturer assures me the Watermaid has no upper limit for salinity - are there other issues with too much salt?
    many thanks
    11k gallon IG Ferrocement , Onga (Pentair) SF750 1hp pump, Onga Pantera MK11 PCF200sqft Cartridge Filter, Watermaid WM40-QT300 SWG, Spa Electrics GK7 LED

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    Mod Squad Bama Rambler's Avatar
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    Re: Pool Fill Water Quality

    The problem with the iron is that it stains, and to keep it from that you have to continually add sequestrant so it's an on-going problem. It's better to pay more and have good metal free water.

    The first thing I'd do s ask for an assay on the trucked in water. The local utility should be able to provide you with one.
    Dave J. TFP Moderator
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    Re: Pool Fill Water Quality

    Quote Originally Posted by Bama Rambler
    The problem with the iron is that it stains, and to keep it from that you have to continually add sequestrant so it's an on-going problem. It's better to pay more and have good metal free water.

    The first thing I'd do s ask for an assay on the trucked in water. The local utility should be able to provide you with one.
    A little googling and I have some info on what they are doing to the water before piping it.
    Not sure whether Iron at 0.014 mg per litre is low enough? (0.3 or lower you say, but I'm not sure on what scale).



    "Having investigated the reservoir environment, our engineers installed a customised, end to end water filtration plant. The water filtration plant was operational within 12 months of project approval.

    Coagulation And Flocculation – This vital stage in the water filtration process prepares water for sedimentation. A coagulant binds together impurities to create denser particles that settle out during the sedimentation process. We installed two flash mixers and flocculation tanks, used to deliver Caustic Acid for pH control and Alum as a coagulant.

    Filtration – the three sand filters installed provide an excellent solution in terms of capacity and purity during the water filtration stage. They can handle rapid flow rates and remove a high level of suspended solids from water. The filters are cleaned by an internal washing system, removing the need for backwashing tanks.
    The result: a compact solution for an abundant supply of clear, clean water.

    Disinfection – chlorine is added prior to storage, to ensure that all micro-organisms in the water are removed.

    The quality of the water supply increased dramatically:
    Water test results demonstrated the following improvements:
    Water turbidity reduced from 8.9 NTU to 0.31 NTU.
    Water colour reduced from 90 HU to < 1HU.
    Aluminium content reduced from 0.644 to o.164 mg/L
    Iron content reduced from 0.841 to 0.014 mg/L
    Manganese content reduced from 0.032 to 0.016 mg/L
    30.03.2010"
    11k gallon IG Ferrocement , Onga (Pentair) SF750 1hp pump, Onga Pantera MK11 PCF200sqft Cartridge Filter, Watermaid WM40-QT300 SWG, Spa Electrics GK7 LED

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    JasonLion's Avatar
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    Re: Pool Fill Water Quality

    I was using ppm, but mg/l and ppm are the same, so .014 is just fine for iron.

    Salt levels much above 5,000 can be a corrosion risk, depending on the materials used in your pool. There are pools that are fine up above 35,000, so there isn't one specific level where problems start, just a varying range of risk.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Pool Fill Water Quality

    Some water option iron test results:

    Groundwater soak: around 0.8 mg/l
    Water tanks containing rainwater:0.0 mg/l

    I'm still waiting for the salt tester to arrive.....

    If the main fill water comes from the water tanks at the start of winter plus some trucked in, is it ok to top up with the
    groundwater in summer, providing a close eye is kept on the iron level as this will be diluted with the pool water or should that water not be used at all?

    PS: that groundwater is also pretty dark and murky looking; I guess that topping up with isnt going to do the clarity of the pool water much good even if it goes through the filter first?

    PPS: I may be getting a localised 'false' reading from the soak as I have been told that the previous owner had the soak filled in with a lot of steel junk then capped with clay. My guess is that the corroded steel in the ground is giving an inflated reading that I might not get in other places. I am going to try some test holes to see if I get the same result. The soak would have been ideal as its not too far from the pool and is significantly lower than other potential spots for water. I guess that even if I had all the steel debris dug out again, the corroded fine particles will continue to affect the iron level in that location?
    11k gallon IG Ferrocement , Onga (Pentair) SF750 1hp pump, Onga Pantera MK11 PCF200sqft Cartridge Filter, Watermaid WM40-QT300 SWG, Spa Electrics GK7 LED

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    Mod Squad Bama Rambler's Avatar
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    Re: Pool Fill Water Quality

    .8 mg/l is kinda high and I wouldn't use it unless I had to. Since the iron was artificially added, you will probably have better luck in a different location. I know it's probably a pain but it will be worth it in the long run.
    Dave J. TFP Moderator
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    Re: Pool Fill Water Quality

    The problem with a new location is that I would probably need to apply for a license which is fraught with probs and limitations on depth/location etc.
    Do you think getting the ground cleaned up (as its a contamination which should never have happened in the first place) will solve the iron prob (if a nearby location yields far lower levels).
    thanks.

    PS: I have another soak much farther away (about 1/4 mile) which although probably has a lot of rainwater in it as we have had some heavy rains recently, yielded a test of zero iron.
    11k gallon IG Ferrocement , Onga (Pentair) SF750 1hp pump, Onga Pantera MK11 PCF200sqft Cartridge Filter, Watermaid WM40-QT300 SWG, Spa Electrics GK7 LED

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    Mod Squad Bama Rambler's Avatar
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    Re: Pool Fill Water Quality

    A good cleanup of the soak, and a few months to clear any residual, will probably lower it enough to work fine. The only problem is that you won't know whether it will work or not until you've done it.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: Pool Fill Water Quality

    Just taken a sample of groundwater. Have allowed the solids to settle for a few hours and then filtered with a paper coffee filter but it is still full of dissolved silt.
    I need enough clear water for the test tube; can anyone advise as to how I can get this sample clear?

    Distillation seems an option but I dont have the glassware required plus I need to make sure I dont lose any iron in the water.
    11k gallon IG Ferrocement , Onga (Pentair) SF750 1hp pump, Onga Pantera MK11 PCF200sqft Cartridge Filter, Watermaid WM40-QT300 SWG, Spa Electrics GK7 LED

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    Mod Squad Bama Rambler's Avatar
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    Re: Pool Fill Water Quality

    You could try doubling the coffee filters and running it through them again. They're not small enough mesh to filter the iron out.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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