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Thread: Can adding a lot of calcium chloride at once reduce FC??

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    Can adding a lot of calcium chloride at once reduce FC??

    I have been a vinyl pool owner for 3 years now, and each year I have tried to tackle a balancing issue. Last year I tackled CYA (I had near 0 and was losing FC rapidly during the day). I used a conditioner to increase CYA to about 50-60, and FC problem solved.

    This year, I am tackling calcium hardness. CH has always tested at about 40ppm using my Taylor K-2006 kit. Yesterday, I broadcast about 25lbs of "Pool Mate Calcium Increase for Swimming Pools" (made by Robelle). It all dissolved very quickly, no cloudiness or white residue. Immediately prior, I tested FC at about 3.0 ppm.

    Good news this morning is CH is testing at a much more reasonable 240 ppm. Bad news is FC is down to 0.6 ppm!!

    I have an SWG (Pentair IC-40) that I generally run at about 40% capacity 24/7 during the summer (next year's project is getting off 24/7!). I checked CYA again this morning and it is around 60ppm, so that's not the culprit for the FC loss. I don't see any algae or organic growth. I jacked up the SWG to 70% output about 3 hours ago, and as of yet, no change in FC.

    My question is: Can adding 25lbs of calcium chloride at once have a short term impact on FC?

    Alternatively, could my SWG be going (I probably have over 10,000 hours on it and have never acid washed)?

    Thanks!
    28,000 gallon lagoon pool, Pentair Intellichlor IC-40 SWG, Pentair IntelliPro Variable Speed Pump, Pentair System 3 Modular Media Filter S7M120, AquaComfort ACT 1500 Heat Pump, waterfall, 2 skimmers, 2 main drains, 3 returns

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    Mod Squad JohnT's Avatar
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    Re: Can adding a lot of calcium chloride at once reduce FC??

    Welcome to TFP!

    Calcium shouldn't have any effect of chlorine. No real need to add it either with a vinyl liner.

    At 60ppm CYA you were right at the minimum FC level and a little glitch could have dropped your chlorine to where algae has gotten started consuming your chlorine.
    TFP Moderator
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    Re: Can adding a lot of calcium chloride at once reduce FC??

    25lbs of Calcium Chloride in your pool size 28k
    should have only raised your CH ~100ppm with a staring point of 40 that means your testing or pool size estimation is off.

    There is no reason to raise the CH in a vinyl lined pool - you can only get rid of it with water change out.

    Take a few swims and see how crusty your hair feels after swimming vs. what it was before
    30k in ground vinyl lined pool surrounded by decking in the woods.
    Hayward sand filter circa mid 80's
    If there is a way to do things less expensively and yield a superior product I am all ears

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    Re: Can adding a lot of calcium chloride at once reduce FC??

    Thanks guys. Pool is vinyl, but we have stone pavers on deck and coping. I had read that soft water would seek out stone and grout and possibly pit pavers, but it sounds like you guys think I didn't need to increase CH. Good news is our water is so soft, that CH will continue to drop as I add water due to evaporation, so I can just let it decrease back to where it was (it's only at about 220 ppm right now).

    FC is up to 3.0 again this morning, but only after I cranked SWG up to 90% about 12 hours ago (usually run at 40%). Don't see any signs of algae. I'll test FC again a midday.

    Interesting point on the FC minimum John. I had always assumed desired FC range is between 2.0-4.0. But using the minimum FC of [4.5% x CYA] from the CYA/Chlorine chart (with an SWG) and assuming CYA of about 50-60, the minimum FC should be about 2.25-2.70. Sounds like I should increase FC closer to 4.0 rather than 3.0.
    28,000 gallon lagoon pool, Pentair Intellichlor IC-40 SWG, Pentair IntelliPro Variable Speed Pump, Pentair System 3 Modular Media Filter S7M120, AquaComfort ACT 1500 Heat Pump, waterfall, 2 skimmers, 2 main drains, 3 returns

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    Mod Squad pooldv's Avatar
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    Re: Can adding a lot of calcium chloride at once reduce FC??

    Please add your location to your profile so it shows up <----- over there. We can give you a better recommendation on CYA level based on that.
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    Mod Squad tim5055's Avatar
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    Re: Can adding a lot of calcium chloride at once reduce FC??

    Quote Originally Posted by Bobkam View Post
    CH will continue to drop as I add water due to evaporation, so I can just let it decrease back to where it was (it's only at about 220 ppm right now).
    CH does not evaporate, it stays behind in the bulk pool water. CH, like CYA only lowers when you pump water out of the pool, water is splashed out of the pool or it is carried out of the pool with wet bating suits and wet dog fur.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Can adding a lot of calcium chloride at once reduce FC??

    Done! I'm in Massachusetts.

    - - - Updated - - -

    Thanks Tim.
    28,000 gallon lagoon pool, Pentair Intellichlor IC-40 SWG, Pentair IntelliPro Variable Speed Pump, Pentair System 3 Modular Media Filter S7M120, AquaComfort ACT 1500 Heat Pump, waterfall, 2 skimmers, 2 main drains, 3 returns

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    Mod Squad tim5055's Avatar
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    Re: Can adding a lot of calcium chloride at once reduce FC??

    How much Pool School have you read? Start with these:
    ABCs of Water Chemistry
    Recommended Pool Chemicals
    How to Chlorinate Your Pool

    The other thing I want to point out is - don't be too concerned chasing "perfect" numbers. Pool stores love to have you chasing numbers by selling you multiple products to raise this, lower that.

    Learn your pool an understand what it likes. Once you have the pH in range, the chlorine is at a sufficient level as compared ot the CYA and the water is clear anything else can be a slow go. No hurries.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Mod Squad pooldv's Avatar
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    Re: Can adding a lot of calcium chloride at once reduce FC??

    Ok, well not a big concern with having CYA at 60 instead of 70 or 80 Although, upping it to 70 will reduce your FC loss to the sun somewhat.
    TFP Moderator
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    Re: Can adding a lot of calcium chloride at once reduce FC??

    Quote Originally Posted by tim5055 View Post
    Thanks Tim. I have read the articles in pool school, and have been able to keep the pool well balanced for the first three years. The recent drop in FC was pretty sudden, leading my original question whether or not it had anything to do with adding the Calcium Chloride (I understand from prior responses above that this is not the case)

    I guess my only other causes are (1) losing FC in sun due to not enough CYA, (2) SWG is losing efficiency (it has over 10,000 hours and has never been acid washed) or, (3) an algae issue. No signs of algae, and pump runs 24/7 keeping lots of flow in the pool.

    FAS-DPD test shows FC has dropped again today from 3.0 early this morning to 2.0 just now, with SWG running at 90% (usually runs at 40-50%). I'm getting more Taylor CYA reagent to retest CYA to see if it has dipped too low. Hopefully I will have enough FC by the end of the day to try an OCLT test tonight.

    Am I missing any other possible causes?
    28,000 gallon lagoon pool, Pentair Intellichlor IC-40 SWG, Pentair IntelliPro Variable Speed Pump, Pentair System 3 Modular Media Filter S7M120, AquaComfort ACT 1500 Heat Pump, waterfall, 2 skimmers, 2 main drains, 3 returns

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