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Thread: 2-part question - backwashing sand filter and metal in water

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    Join Date
    Jul 2015
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    Sault ste Marie, Ontario, Canada
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    2-part question - backwashing sand filter and metal in water

    Hi there,
    We just finished our pool build last fall (just in time to close it). Well, 90% complete, our pool guy is coming to install the SWG as soon as we have the pool opened (we're using chlorine pucks in the skimmers in the meantime).

    We took the cover off of the pool yesterday and are currently cleaning and topping it up with water. The pool is extremely dirty (brown) and cloudy mostly due to dirt and leaves I believe. We ran our dolphin triton robotic vacuum most of yesterday. It is picking up tons of leaves (and frogs!) and dirt and the filters are very slimey when we pull the vacuum out to empty and clean the filters. I haven't tested the chemicals yet (will do later today), but I'm assuming I will need to slam it.

    My 1st question is regarding the backwash process:
    Since we are new pool owners we do not know what a normal pressure level is for us. So how will we know when to backwash? I am concerned about backwashing more than necessary because we have limited water source (well) and it is expensive to bring water in where we live.

    My 2nd question is about metal in the water:
    Our well water occasionally has iron in it. Do I need to test for metals in my pool? If so how and how often? Should I add sequesterant (?) as a precaution. We have no choice but to use well water.

    thanks!
    22' x 44' rectangular IG vinyl liner swimming pool with SWG, 10' depth in deep end, 44,000 gallons. Pump: Pentair Superflow 1.5 HP High Performance Pump. Filter: Pentair Sand Dollar Filter. Location: Ontario, Canada

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    Pool Tool's Avatar
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    May 2014
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    Western Chicago Area, IL
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    Re: 2-part question - backwashing sand filter and metal in water

    Question 1 - Backwash it now. Do it for two minutes then rinse for thirty seconds. Turn back to filter and check pressure. This is your clean pressure, only backwash after a 25% rise from clean.

    Question 2 - Knowing your well has iron is good. Use the search tool to look up iron filters folks have used on the their hose ends while filling. I know my well has iron and I do nothing different. This might bite me in the butt one day, but until then I treat it as fine. You can also divert rain water to the pool to top it off when possible. Unless you see staining or something, I personally would not use a sequester. Additionally, this is a example of a time that pool store testing is recommended. Just take your results, buy a jug of chlorine then run.

    My question - what are you using to verify CYA/FC levels with the tabs and then when the SWG is running?
    16' x 32' (21100 gal), vinyl, 1.5 hp Hayward SuperPump,
    Tagelus TA60/60D Sand Filter, Raypak 399K Digital Heater, TF-100

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    Kiss4aFrog's Avatar
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    May 2013
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    Re: 2-part question - backwashing sand filter and metal in water

    Did you backwash the filter when you closed the pool ?? If so when you started it up this year you should be seeing the "clean" pressure you'd use as a guide. Pool School - Maintenance and Cleaning of Pool Filters
    '70s IG Vinyl 32K gal, Lazy L, Hayward SuperPump 1.5hp 120V, S240 Sand Filter W/DE
    Solar Blanket, Well Water, Borax Added, TF-100 tester. ? too cold
    1979, 275gal Conway Emerald Spa P-100-2, ES-2 Spa Pack, bromine floater, indoor
    TF-100, Best test kit - TFTestkits.net
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    Join Date
    Jul 2015
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    Sault ste Marie, Ontario, Canada
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    Re: 2-part question - backwashing sand filter and metal in water

    I think we backwashed it right before draining it?

    - - - Updated - - -

    We have the Taylor k 2006 testing kit.

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    duraleigh's Avatar
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    Apr 2007
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    Sebring, Florida
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    Re: 2-part question - backwashing sand filter and metal in water

    So if you have iron in your well water, it is in your pool as well. Test for it to see what your up against but the only way to "treat" it is to keep it suspended in solution......that's what the sequestrant does. It never removes any iron....just forces it into soluble form.

    The problem is is it gets weak and must be replenished over and over as the iron tries to precipitate......a never ending battle and sequestrants are the best device you can use to hold it at bay.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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