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Thread: SLAMing an Indoor Pool

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    SLAMing an Indoor Pool

    Hello all!

    We're very excited to have bought a home with an indoor pool - recently acid washed, tile completely re-grouted, new filter, new fill, currently being kept at about 60 degrees (since the house is unoccupied) and with crystal clear water.

    Talked to the person currently maintaining the pool, and he's very easily managing to keep it at about 3 PPM of free chlorine right now - but nobody is swimming in it.

    I'm not expecting to have to fix anything on taking possession (except temperature, of course) - but I will definitely be buying a proper test kit, and using the TFP method. I'm very comfortable with the chemistry.

    This does lead to a question though - knowing that the pool loses very little free chlorine when things are in good shape, is it recommended to shock it with something other than chlorine (i.e. monopersulfate)? I've done a ton of reading on the forums, and this hasn't seemed to pop up anywhere. I'd hate to put the pool out of commission for a week waiting for it to come down from 10 PPM (if that's the shock level to use) if/when the time comes that SLAMing is necessary.

    Thanks for any thoughts, and happy to be a new member!

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    In the Industry

    Donldson's Avatar
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    Re: SLAMing an Indoor Pool

    Welcome to the forum!

    First thing to remember is that if you take care of it properly you will never need to SLAM. SLAMing is only for when something goes wrong, so the first thing to do is maintain everything properly and avoid it

    Next, there is no reason to wait, you can swim right up to SLAM level assuming you have CYA in the water. If you really want to drop it down quickly you can use a chlorine neutralizer or hydrogen peroxide to drop it, but there really is no need. As far as using MPS, the only time I know of that it is really of much use is if you have a buildup of CC, but someone with an indoor pool may have better advice regarding that.
    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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    JoyfulNoise's Avatar
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    Re: SLAMing an Indoor Pool

    It's all going to depend on bather load and how quickly organics oxidize. Do you have a supplemental form of disinfection such as a UV system or an ozone system? Or both?

    In an indoor pool, there is little to no UV light getting to the pool. Outdoor UV light acts as both a supplemental form of oxidation for CCs as well as a source for creating powerful hydroxyl radicals that also help to eliminate CCs. Depending on your bather load and the level of CCs that accumulate, you may need a supplemental form of oxidation. Potassium monopersulfate (MPS) can help with this but two things will occur - you will build up sulfates in your water over time requiring you to exchange out water more frequently AND the MPS will interfere with your FC testing (DPD-FAS testing). If you use MPS, then you should order their additional MPS Interference Removal Kit .

    Again, it's going to depend heavily on bather load and cleanliness.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Mod Squad kimkats's Avatar
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    Re: SLAMing an Indoor Pool

    Do you have any pics you can share?

    You are on the right track already with your test kit! You will never be pool stored! SWEET!

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Isaac-1's Avatar
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    May 2010
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    Re: SLAMing an Indoor Pool

    Welcome fellow indoor pool owner, as has already been stated a lot is going to depend on bather load, but I can tell you from my personal experience that if I maintain a good balanced pool I don't often need to use MPS. However every pool is different and mine does get a slight amount of UV exposure while mine is indoors there is a 6x40 foot polycarbonate skylight over the pool which allows a swath of sunlight to pass across the pool each day as well as sliding glass doors on the east and west sides of the building, both of which likely pass a fraction of the UV light from the sun. The only time I find I need to use MPS is after a large group has been swimming, and even then it tends to only be needed if there is a large group swimming on multiple days. In the case of my pool this is a fairly rare event these days, and may happen less than once per year. Last summer I did have one event that required me to use MPS, where we had 2 groups with about 25 - 30 swimmers using the pool using the pool with one day break between them. (it should be noted that MPS shows as CC on the common test which adds to the confusion regarding its use, so if you plan to use it regularly you may wish to invest in the special Taylor MPS elimination test kit)

    As to the shocking issue, I also try to avoid it usually with fairly good success, but things do happen, like equipment failures in the summer, or even the occasional I don't know exactly why it happened algae bloom that can be caused by poor circulation, and algae getting a toehold under a pool ladder step, etc. Thankfully if you keep things balanced using the TFP method this will likely be a very rare event rare event, since switching to this method nearly 6 years ago, I have only needed to go through a short SLAM process 2 or 3 times and even then it was only done due to testing showing an abnormal chlorine consumption, not a visibly green pool. If you are still concerned about the extended time it takes for FC to drop to safe swim levels you can use a chlorine neutralizer, but be aware that use of these products can also cause your post slam testing result to act a bit wonky which may cause confusion of if you have successfully killed everything that was trying to grow in your pool.

    There is a lot more to cover about indoor pool differences, but that can wait until you can tell us about your pool, and you get a good test kit in hand and we have some reliable numbers to worth with.

    Ike
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
    I use and endorse TFtestKits TF-100 from http://tftestkits.net
    ~Remember TFP counts on your donations to keep this site ad free~

  6. Back To Top    #6

    Join Date
    Feb 2016
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    Near Toronto, Ontario
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    Re: SLAMing an Indoor Pool

    Oops, was on a different computer, I think I have two user ids on here. Mods - there is a posting from me under a different user name - you can delete that.

    I will post more information when the pool becomes ours (February 29th) and post test results as well. I will see about some pictures too.

    We're really excited - it's too bad it will be too cold to swim in for a couple days as we heat it up, 60 degrees is just too cold!

    I thought it was in my signature - approximately 22,000 gallon indoor pool, details to follow!

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