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Thread: Just converted to SWG, chlorine demand went way up!

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    Just converted to SWG, chlorine demand went way up!

    Hi.

    I just converted to a SWG from regular bleach this year. I have the Hayward Aquarite working great and all the plumbing and electrical is good. My chorine level has been steady for weeks now with bleach and was sitting at around 5 ppm last night.

    I just dumped in my bags of salt this morning to get up to 3200 ppm, and an hour later I checked my chorine with my TF-100 test kit and it's at around 0.5 ppm. I just dumped in another 121 oz of 8.25% and will check again soon.

    Is this common for the salt to increase the chlorine demand, at least initially? What else could be going on?

    Thanks,
    Dino

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    Mod Squad JVTrain's Avatar
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    Re: Just converted to SWG, chlorine demand went way up!

    Unless the salt was contaminated with some other organic substance, salt should not affect your chlorine demand.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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    mikemass's Avatar
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    Re: Just converted to SWG, chlorine demand went way up!

    Dino. How can you be sure it's your Cl demand that increased? It sounds more like your salt cell is not producing. Do you have the %'age bumped up to a decent number on your Aqua-Rite? How long is your pump run time? And lastly what are your other chemistry readings? Namely CYA?
    25 + year pool owner. Current pool (going on 11th year) - 38K gallon in ground Gunite/White Plaster, Spillover Spa, Hayward Cartridge Filter, Hayward 450k BTU NG Heater, Hayward Goldline Aqua Logic control with T-Cell-15 Salt Water Cell, Dolphin Explorer.
    You Need: Bleach, a A Test Kit & a Bookmark to "Pool School". Now what's your question?

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    Re: Just converted to SWG, chlorine demand went way up!

    SWG is set initially at 50%. CYA is 60 and I just measured FC and CC again. FC is at 1 and CC at 1. So something is definitely in the water consuming FC. I am bringing to SLAM level now.

    I just don't think it was a coincidence that on the first day I dump in the salt for my new SWG the chlorine demand is now up.

    I should have measured my chlorine before adding the salt but I didn't. The only other thing I can thing of is that when I removed my solar cover this morning, a LOT of yellow pollen dropped into the pool. It rained a bit last night so the pollen just dumped into the pool as I removed the cover.

    Could the pollen be the culprit?

    Thanks.

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    mikemass's Avatar
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    Re: Just converted to SWG, chlorine demand went way up!

    if you haven't brought the pool to SLAM level yet with bleach try setting the cell to 100%. Let it run for 10 mins and get a water sample directly in front of a return. I want to see you rule out a problem with the cell first. Maybe pollen is the culprit in which case I would run the SWG on a higher output until this pollen subsides. (Assuming the cell is good)
    25 + year pool owner. Current pool (going on 11th year) - 38K gallon in ground Gunite/White Plaster, Spillover Spa, Hayward Cartridge Filter, Hayward 450k BTU NG Heater, Hayward Goldline Aqua Logic control with T-Cell-15 Salt Water Cell, Dolphin Explorer.
    You Need: Bleach, a A Test Kit & a Bookmark to "Pool School". Now what's your question?

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    Re: Just converted to SWG, chlorine demand went way up!

    Interesting...something similar happened to me last week as well.

    FC was at SLAM level (12 or 13ppm). CC was 0.5 or maybe even less.

    Added the 200 lbs of salt I usually add every season to bring salt level back up.

    The next morning FC was all the way down to 1.0 and CC was 1.0. I know my CYA is low, but all measurements were done with the sun down, so nothing should have eaten up that much FC overnight. The water is cloudy but blue. FC was at that high level for 2+ days with very little additions during those days.

    The *only* thing that changed was the addition of the salt....seriously wonder if there was something in it. It all looked "clean" as I poured it in, but who knows.
    22K IG vinyl, .5HP Northstar pump, S244T filter, AutoPilot Digital w/SC-48 cell

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    Saturn94's Avatar
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    Re: Just converted to SWG, chlorine demand went way up!

    Strange. I've never experienced a FC drop like that from adding salt.
    20k IG vinyl liner/Aqua Rite SWCG, T-15 cell/Hayward Pro Grid 6020 DE filter/Polaris 280 with booster pump/Hayward Superpump 1 hp/city water/pool installed March 2004

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    Re: Just converted to SWG, chlorine demand went way up!

    I used Morton pool salt from Walmart. The bag reads "Medium Grade" whatever that means. I have brought my FC up to shock level and hoping that solves this quickly.

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    mikemass's Avatar
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    Re: Just converted to SWG, chlorine demand went way up!

    Same salt I use. I never noticed the term "medium" on there. But I do know the bags say "High Purity"
    25 + year pool owner. Current pool (going on 11th year) - 38K gallon in ground Gunite/White Plaster, Spillover Spa, Hayward Cartridge Filter, Hayward 450k BTU NG Heater, Hayward Goldline Aqua Logic control with T-Cell-15 Salt Water Cell, Dolphin Explorer.
    You Need: Bleach, a A Test Kit & a Bookmark to "Pool School". Now what's your question?

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    Re: Just converted to SWG, chlorine demand went way up!

    Same here, Morton Pool Salt.

    Oddly enough I *usually* use Diamond Solar Salt from Lowes, but Walmart had the Morton stuff at the same price so I went with "real" pool salt instead.
    22K IG vinyl, .5HP Northstar pump, S244T filter, AutoPilot Digital w/SC-48 cell

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    Re: Just converted to SWG, chlorine demand went way up!

    Just an FYI, someone else I know used Morton Pool Salt this year and experienced the same massive overnight FC drop.
    22K IG vinyl, .5HP Northstar pump, S244T filter, AutoPilot Digital w/SC-48 cell

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    Re: Just converted to SWG, chlorine demand went way up!

    Interesting Chris.

    Just FYI, after SLAMing the pool I am now good and the chlorine demand is very low each day (normal). I am still trying to figure out the run % for my SWG and pool. Starting at 50% for 10 hour runtime seems to be too much, so I lowered to 40%.

    Dino
    Premier (Esther Williams) 24' x 52" Round AGP (13,500 gl.), Hayward 24" Pro-Series S244T Sand Filter, 1.5 HP Hayward Super Pump, AquaRite SWG, AquaComfort ACT-1100 Heat Pump, Jandy/Zodiac iAqualink Automation System with iPhone App, Aquabot Pool Rover S2-40
    My New Pool

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    Mod Squad JVTrain's Avatar
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    Re: Just converted to SWG, chlorine demand went way up!

    Has anyone who experienced this chlorine demand after adding salt contacted the manufacturer? It would be good to make them aware or perhaps they can find a reason.

    Sent from mobile device. Beware of brevity and spelling errors!
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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    Re: Just converted to SWG, chlorine demand went way up!

    I just assumed it was me...while my chem levels seem correct it could just have been a fluke or there really was something eating that much FC overnight (doubtful but who knows)

    For the heck of it I emailed Morton support. Interested if they come back with any info. Ill post an update if they do.
    22K IG vinyl, .5HP Northstar pump, S244T filter, AutoPilot Digital w/SC-48 cell

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