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Thread: Low Chlorine after algaecide

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    Low Chlorine after algaecide

    I was starting to see a little green algae in my pool, Chlorine was around 3 (I usually run 4-6) and I told my pool guy. The next day he told me he added algaecide (I don't know what kind) and a gallon of Chlorine. Today, two days later, I was doing my routine testing and see that Chlorine is less than 1 on several different samples with different test kits, including FAS-DPD. I texted my pool guy and he said don't worry. the algaecide masks the chlorine test. It'll be fine. I've never heard that and can't find it referenced online. Information please? Thanks.
    30,000 gallon pebble-tec in-ground pool. Jandy Aquapure 1400 salt system. 1.5 hp fixed speed pump. IAqualink integrated system- pump, spa, SWG, lights. Kreepy Krauly. Rooftop Solar heater (on pool pump). Taylor K2006 test kit. SoCal, near Los Angeles - sunny and hot. Local well water, very hard.

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    Mod Squad pooldv's Avatar
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    Re: Low Chlorine after algaecide

    It does not mask FC it consumes FC. And some also add copper which can stain pools, water, hair, nails, kids and dogs.
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    Re: Low Chlorine after algaecide

    So do I need to add more chlorine/shock right away to get those levels back up? The pool is not green - yet...
    30,000 gallon pebble-tec in-ground pool. Jandy Aquapure 1400 salt system. 1.5 hp fixed speed pump. IAqualink integrated system- pump, spa, SWG, lights. Kreepy Krauly. Rooftop Solar heater (on pool pump). Taylor K2006 test kit. SoCal, near Los Angeles - sunny and hot. Local well water, very hard.

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    Re: Low Chlorine after algaecide

    What Pooldv said ! ! ! !

    Yes you need to add to get back up to your 4-6 norm. You might want to run a CC test just to see where you're at but I would sure request the pool guy not use algacide in my pool again.
    It might be one that contains copper among other things and it's just not needed if you maintain your FC. That, and it can cause more problems then it solveds.
    The other thing about algacide is that if you're seeing a little green you likely already have algae and algacide only prevents algae, it doesn't kill it.
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    Mod Squad pooldv's Avatar
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    Re: Low Chlorine after algaecide

    Fc needs to be maintained above minimum for your cya at all times to keep the pool safe, sanitary and algae free. FC/CYA Chart
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    Re: Low Chlorine after algaecide

    Thanks. I've been through all of this and a SLAM before and think I understand everything. After adding shock yesterday, I tested total and FCl today, it's up to 5. I'm happy with that. What I'm not happy with is that I ran a full panel and came up with CYA of 120! It's always stayed around 80 and we haven't added any stabilizer in recent memory. What could cause it to jump up like that? I live in Southern California and water now is quite expensive so I really don't want to do any draining. Thoughts? BTW pH 7.6, TA 80.
    Thanks,
    Russ
    30,000 gallon pebble-tec in-ground pool. Jandy Aquapure 1400 salt system. 1.5 hp fixed speed pump. IAqualink integrated system- pump, spa, SWG, lights. Kreepy Krauly. Rooftop Solar heater (on pool pump). Taylor K2006 test kit. SoCal, near Los Angeles - sunny and hot. Local well water, very hard.

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    Mod Squad pooldv's Avatar
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    Re: Low Chlorine after algaecide

    How are you chlorinating the pool? Pucks and powdered chlorine add CYA. More here, Pool School - How to Chlorinate Your Pool
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    Re: Low Chlorine after algaecide

    Quote Originally Posted by Russmd View Post
    Thanks. I've been through all of this and a SLAM before and think I understand everything. After adding shock yesterday, I tested total and FCl today, it's up to 5. I'm happy with that. What I'm not happy with is that I ran a full panel and came up with CYA of 120! It's always stayed around 80 and we haven't added any stabilizer in recent memory. What could cause it to jump up like that? I live in Southern California and water now is quite expensive so I really don't want to do any draining. Thoughts? BTW pH 7.6, TA 80.
    Thanks,
    Russ
    what kit are you using? It would help if you could add its name to your signature so nobody would ever ask again .
    My reason is the 2 recognized kits K2006 / TF100 can go up to 100 CYA max and you indicated yours is at 120. Did you use dilution?
    44k plaster pool, Pentair 011018 pump, DE6020 filter, LED lights, K2006 test kit

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    Re: Low Chlorine after algaecide

    We get confused when you use SLAM and shock in the same sentence. To maintain and SLAM a pool we use chlorine which doesn't have any CYA in it. We normally think of "shock" as the powder sanitizer and most have CYA in them along with those chlorinating tablets.
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    Solar Blanket, Well Water, Borax Added, TF-100 tester. ? too cold
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    Re: Low Chlorine after algaecide

    You are all very helpful and I am starting to get it now. I shouldn't have used the SLAM term in this case. I just re-read the chlorinating section in Pool School. I may have inadvertently caused the CYA problem - when, at the beginning of this thread, I noted the very low FCl level, I panicked and threw in 5 lbs of granular shock. My FCl rose to 5, but that's when I noticed the higher CYA level too. I did not remember there's CYA in granular chlorine. I use the Taylor K2006 test kit and I extrapolated the CYA to about 120 since the high on the tube is 100.

    So, what to do now. As I was thinking of, I will not install an in-line puck chlorinator to supplement the SWG. I will use liquid chlorine to supplement. Unfortunately, during the hot summer, my SWG can't keep up even if if I run it at 100% 12 hours a day, it scales very badly requiring cleaning every 3 weeks. I'm sure the cell will burn out at this rate. We have very hard water supply here and calcium hardness is impossible to battle. pH and TAlk are optimized at 7.6 and 80.

    Any other recommendations to:
    - increase chlorination another way, other than adding liquid chlorine once or twice a week?
    - reading about chlorine sources, thoughts about bleach vs the 12.5% chlorinating liquid?
    - looks like the liquid chlorinator a will raise the salt levels. Significant in my salt pool?
    - any way to bring that CYA level down without draining (very expensive water here).

    Thanks,
    Russ
    30,000 gallon pebble-tec in-ground pool. Jandy Aquapure 1400 salt system. 1.5 hp fixed speed pump. IAqualink integrated system- pump, spa, SWG, lights. Kreepy Krauly. Rooftop Solar heater (on pool pump). Taylor K2006 test kit. SoCal, near Los Angeles - sunny and hot. Local well water, very hard.

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    Re: Low Chlorine after algaecide

    - You could get a bigger SWG, sized to twice your pool size. There are also Stenner chlorinators

    - Bleach and chlorinating liquid are the same thing. Go with the best $/% value (haha that looks like swear words!)

    - Not sure I follow? Bleach has salt in it, but not that much.

    - I've heard rumors of reverse osmosis to reduce CYA. Otherwise, no. You just have to be very creative, things like diverting all gutters to the pool, cannonball parties, etc.

    If you could add your location to your profile that would be helpful, to know what kind of water you have, how much sun you get, etc.
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    Re: Low Chlorine after algaecide

    Quote Originally Posted by Russmd View Post
    You are all very helpful and I am starting to get it now. I shouldn't have used the SLAM term in this case. I just re-read the chlorinating section in Pool School. I may have inadvertently caused the CYA problem - when, at the beginning of this thread, I noted the very low FCl level, I panicked and threw in 5 lbs of granular shock. My FCl rose to 5, but that's when I noticed the higher CYA level too. I did not remember there's CYA in granular chlorine. I use the Taylor K2006 test kit and I extrapolated the CYA to about 120 since the high on the tube is 100.

    So, what to do now. As I was thinking of, I will not install an in-line puck chlorinator to supplement the SWG. I will use liquid chlorine to supplement. Unfortunately, during the hot summer, my SWG can't keep up even if if I run it at 100% 12 hours a day, it scales very badly requiring cleaning every 3 weeks. I'm sure the cell will burn out at this rate. We have very hard water supply here and calcium hardness is impossible to battle. pH and TAlk are optimized at 7.6 and 80.

    Any other recommendations to:
    - increase chlorination another way, other than adding liquid chlorine once or twice a week?
    - reading about chlorine sources, thoughts about bleach vs the 12.5% chlorinating liquid?
    - looks like the liquid chlorinator a will raise the salt levels. Significant in my salt pool?
    - any way to bring that CYA level down without draining (very expensive water here).

    Thanks,
    Russ
    Please fill in your location in the profile so we'd know climate zone you're in.

    I'd turn SWG (not the pump) off for now until you get a grip of your water balance and measure how much FC your pool requires. Your SWG produces 1.25 lb of chlorine gas/day which is equivalent to 8ppm FC for your pool size so it should be ON for only 25-30% time. It appears algae is consuming FC in your pool and no SWG will be able to keep up with that. Once you get your water balanced you should see < 2ppm FC daily loss and your SWG at that point should be able to keep up.

    12.5% chlorinating liquid is better in a sense you have to carry less water around, otherwise it's the same sodium hypochlorite

    Liquid chlorine will raise salt by so insignificant value it will be compensated by draining the pool during back washing. This is not a problem, especially since you have salt pool.

    You need to use dilution 1:1 to get more accurate value of CYA- get equal amounts of pool water and distilled (or tap) water into some clean container, mix them together, test the mix and multiply result by 2. Problem with CYA testing is any value above 100 shows as '100'.

    Can you post all your test results in one run in the following format just to get a reference point :

    FC=
    CC=
    CYA=
    pH=
    TA=
    CH=
    44k plaster pool, Pentair 011018 pump, DE6020 filter, LED lights, K2006 test kit

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    Re: Low Chlorine after algaecide

    Thanks. Reading the article in pool school about chlorinating options, it states that liquid bleach adds salt to the pool so I wanted to make sure that won't be significant. I'm at 3600 as it is.
    Any $ experience about buying chlorinating liquid at the pool store vs weaker bleach at Costco?
    I've been reading about the Bioactive CYA reduced but sounds like it's a no-go.
    I'm just north of Los Angeles, sunny and hot. Well water, very hard.

    - - - Updated - - -

    Quote Originally Posted by max2k View Post
    Please fill in your location in the profile so we'd know climate zone you're in.

    I'd turn SWG (not the pump) off for now until you get a grip of your water balance and measure how much FC your pool requires. Your SWG produces 1.25 lb of chlorine gas/day which is equivalent to 8ppm FC for your pool size so it should be ON for only 25-30% time. It appears algae is consuming FC in your pool and no SWG will be able to keep up with that. Once you get your water balanced you should see < 2ppm FC daily loss and your SWG at that point should be able to keep up.

    12.5% chlorinating liquid is better in a sense you have to carry less water around, otherwise it's the same sodium hypochlorite

    Liquid chlorine will raise salt by so insignificant value it will be compensated by draining the pool during back washing. This is not a problem, especially since you have salt pool.

    You need to use dilution 1:1 to get more accurate value of CYA- get equal amounts of pool water and distilled (or tap) water into some clean container, mix them together, test the mix and multiply result by 2. Problem with CYA testing is any value above 100 shows as '100'.

    Can you post all your test results in one run in the following format just to get a reference point :

    FC=
    CC=
    CYA=
    pH=
    TA=
    CH=

    Will do later, thanks.
    30,000 gallon pebble-tec in-ground pool. Jandy Aquapure 1400 salt system. 1.5 hp fixed speed pump. IAqualink integrated system- pump, spa, SWG, lights. Kreepy Krauly. Rooftop Solar heater (on pool pump). Taylor K2006 test kit. SoCal, near Los Angeles - sunny and hot. Local well water, very hard.

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    Re: Low Chlorine after algaecide

    Quote Originally Posted by Russmd View Post
    Thanks. Reading the article in pool school about chlorinating options, it states that liquid bleach adds salt to the pool so I wanted to make sure that won't be significant. I'm at 3600 as it is.
    Any $ experience about buying chlorinating liquid at the pool store vs weaker bleach at Costco?
    I've been reading about the Bioactive CYA reduced but sounds like it's a no-go.
    I'm just north of Los Angeles, sunny and hot. Well water, very hard.



    - - - Updated - - -




    Will do later, thanks.
    For every 1ppm of FC added with 10% liquid, you will add about 1.6ppm of salt. If you add 20ppm of FC a week, you will also add 32ppm salt. In ten weeks you've added 320ppm of salt.

    In contrast, for every 1ppm of FC added with dichlor, you will add about 0.9ppm CYA. With 20ppm of FC added per week, you will also add 18ppm CYA. In just 5 weeks you will have added 90ppm of CYA and have an un-manageable pool.

    You can use the link in this post to find your true chlorine cost:
    http://www.troublefreepool.com/threa...ine-calculator

    A few members here have tried the Bio-Active with poor results. A quick search on the forum will bring up those posts.

    HTH
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    Re: Low Chlorine after algaecide

    Quote Originally Posted by Kiss4aFrog View Post
    We get confused when you use SLAM and shock in the same sentence. To maintain and SLAM a pool we use chlorine which doesn't have any CYA in it. We normally think of "shock" as the powder sanitizer and most have CYA in them along with those chlorinating tablets.
    This is great powder shock w/o the CYA:

    http://www.intheswim.com/p/super-pool-shock#pdp-tab3

    "Our non-stabilized formula is ideal for shocking."
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    Re: Low Chlorine after algaecide

    Quote Originally Posted by s1njin View Post
    This is great powder shock w/o the CYA:

    http://www.intheswim.com/p/super-pool-shock#pdp-tab3

    "Our non-stabilized formula is ideal for shocking."
    ^^^^ Only if you don't have a problem with CH - looks like he already does (pending him providing a full set of test results).

    Regular bleach sounds like a better solution - cheapest strongest you can find locally...
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    Re: Low Chlorine after algaecide

    True, I'm always in the low to mid 200s. And w/ the backwashing and adding fresh, I never really climb where I need to worry. That's just me though. I find the powder shock to be a heaven sent; I can't imagine all the gallons of bleach I'd need to have on hand otherwise.
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    Re: Low Chlorine after algaecide

    Thanks. Can't wait to get home and get the test kits out! Results pending.
    30,000 gallon pebble-tec in-ground pool. Jandy Aquapure 1400 salt system. 1.5 hp fixed speed pump. IAqualink integrated system- pump, spa, SWG, lights. Kreepy Krauly. Rooftop Solar heater (on pool pump). Taylor K2006 test kit. SoCal, near Los Angeles - sunny and hot. Local well water, very hard.

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    Re: Low Chlorine after algaecide

    Quote Originally Posted by s1njin View Post
    This is great powder shock w/o the CYA:

    http://www.intheswim.com/p/super-pool-shock#pdp-tab3

    "Our non-stabilized formula is ideal for shocking."
    That is 73% Cal-Hypo..... Chlorine stabilized with calcium.

    In a 25000 gallon pool every 4.5oz will add 1ppm FC, 0.7ppm CH, & 1ppm salt.

    Too much calcium in pool water leads to scaling and cloudy water. The only way to lower CH & CYA is with water exchange (drain & refill).
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    Re: Low Chlorine after algaecide

    Here are the results, double-checked for accuracy:

    FC 7.5
    CC 0
    CYA 120 (1:1 dilution method)
    pH 7.7
    TA 70
    CH 850 (double checked)
    Salt 3600

    I'm really hesitant to partially drain and refill at this point due to water restrictions and cost.
    Recommendations, including type of chlorine supplement if I need it.

    Thanks,
    Russ
    30,000 gallon pebble-tec in-ground pool. Jandy Aquapure 1400 salt system. 1.5 hp fixed speed pump. IAqualink integrated system- pump, spa, SWG, lights. Kreepy Krauly. Rooftop Solar heater (on pool pump). Taylor K2006 test kit. SoCal, near Los Angeles - sunny and hot. Local well water, very hard.

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