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Thread: Bleach question

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    j_m_min's Avatar
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    Bleach question

    I have been following the bleach as chlorine method since april and I have been following this site since january.

    I drained pool to drop the CYA from around 200.

    My CYA is now about 50.

    Up until recently I have been adding a half bottle, 60 oz, 8.25% bleach every day into my 25,000 gallon pool. FC in morning is about 2, it goes to 4 then back down to 2 the next morning.

    Since it is been getting real hot in Houston in July, does it make sense that I need to be adding more chlorine to maintain these levels? Is the chlorine dissolved by the sun only or does temperature play a factor in it?

    Barely anyone swims in the pool. Last week we had about 8 people in the pool for 3 hours. The next day I noticed some yellow algae on the walls in patches, about 20. I immediately brushed them off and added 3 full bottles of bleach for 3 days to get FC up to 20 which the chart says I needed to do. ALgae is gone. Do I sit and wait to see if the algae back or is there something proactive I am supposed to do.

    This may seem like a stupid question, but if a pool has a higher FC level, does more chlorine dissolve in the water over time? example: if FC is 2 and I add bleach to get it to 4, it is back to 2 in the morning. If I add twice the bleach and get it to six, will it lose 2 FC and be 4 in the morning? because it always seems to get back to 2, even when I add more bleach. To put it a stupid way, if I add half a bottle of bleach a day, I am good. If I added 4 bottles of bleach on Sunday, would I still be good on saturday or would more chlorine dissolve since more is exposed to the sun?
    25,000 IG plaster pool. DE Pentair 60 gallons. Hayward pump with Single speed AO Smith 2.4 hp motor. Pool installed probably 20 yrs ago. Taylor water tesing kit.

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    Texas Splash's Avatar
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    Re: Bleach question

    J_M, in our area it has been extremely hot this week. My pool gets sun from 7:00am to 9:00pm. I know the feeling. But I can't imagine having my FC level as low as 2 or even 4. Of course every pool is different, but remember - at a CYA of 50, your minimum is FC 4 according to the Pool School - Chlorine / CYA Chart, with a target FC of 6. I would never let mine go below 6 at running the risk of algae. In fact, I just raised my CYA to 60-ish to try and save on bleach.

    How much FC you use depends naturally on the amount of UV/Sun, debris in the water, swimming, and your CYA. Ideally, when your CYA and FC are matched together based on the chart, the rate of FC loss should be somewhat consistent, 2-3, maybe 4 ppm each day depending upon all those factors. Of course with a high CYA, you'll have a slightly higher target, but that's to increase sun protection, so the FC loss should be comparable to someone with a lower CYA who maintains lower FC levels. Hope that makes sense.

    Still, if I were you, I'd punch-up that FC right away, and since you appear to be seeing algae/cloudiness, do a SLAM now in hopes of finishing it sooner. After that, always ensure that FC stays at or slightly above the target of FC 6 based on your CYA of 50. If you find that you lose bleach (FC) too fast on these hot days, maybe increase CYA slightly. Just a thought.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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    Mod Squad JVTrain's Avatar
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    Re: Bleach question

    Chlorine loss more typically follows a percentage base loss rather than a fixed concentration or ppm loss. For instance your example of 4 ppm dropping to 2 ppm over the course of the day would be a 50% loss in chlorine. If you raised it to 6 ppm, I would expect something closer to a 3 ppm FC loss, 50% of the initial value.

    As Texas Pat says, KEEP THAT FC AT OR ABOVE 4 ppm.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
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    Re: Bleach question

    Quote Originally Posted by j_m_min View Post
    I have been following the bleach as chlorine method since april and I have been following this site since january.

    I drained pool to drop the CYA from around 200.

    My CYA is now about 50.

    Up until recently I have been adding a half bottle, 60 oz, 8.25% bleach every day into my 25,000 gallon pool. FC in morning is about 2, it goes to 4 then back down to 2 the next morning.

    Since it is been getting real hot in Houston in July, does it make sense that I need to be adding more chlorine to maintain these levels? Is the chlorine dissolved by the sun only or does temperature play a factor in it?

    Barely anyone swims in the pool. Last week we had about 8 people in the pool for 3 hours. The next day I noticed some yellow algae on the walls in patches, about 20. I immediately brushed them off and added 3 full bottles of bleach for 3 days to get FC up to 20 which the chart says I needed to do. ALgae is gone. Do I sit and wait to see if the algae back or is there something proactive I am supposed to do.

    This may seem like a stupid question, but if a pool has a higher FC level, does more chlorine dissolve in the water over time? example: if FC is 2 and I add bleach to get it to 4, it is back to 2 in the morning. If I add twice the bleach and get it to six, will it lose 2 FC and be 4 in the morning? because it always seems to get back to 2, even when I add more bleach. To put it a stupid way, if I add half a bottle of bleach a day, I am good. If I added 4 bottles of bleach on Sunday, would I still be good on saturday or would more chlorine dissolve since more is exposed to the sun?
    No, once you put the liquid Chlorine in the water and it is fully distributed, the FC is as high as it will get. If the dose was enough to get you to 7PPM you'll have it right then, and perhaps for some reasonable period of time, depending on many factors. From there it will decline, again depending on those factors. Bather load, other organic matter including Algae/spores, and of course sun exposure.

    You got Algae not because of the bather load, but because you had been running your FC too low, too often prior to that event. No harm done, learn from it and move on. I would say a SLAM might be in order for you to be sure you've killed it all. If it were mine, that's what I would determine, and likely do.
    TFP Moderator
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    Re: Bleach question

    Quote Originally Posted by j_m_min View Post
    Last week we had about 8 people in the pool for 3 hours. The next day I noticed some yellow algae on the walls in patches, about 20. I immediately brushed them off and added 3 full bottles of bleach for 3 days to get FC up to 20 which the chart says I needed to do. ALgae is gone. Do I sit and wait to see if the algae back or is there something proactive I am supposed to do.
    How did you determine the algae was gone?

    Please read through pool school, especially the SLAM procedure. If you follow the SLAM to a T, you'll have that algae beat for good.

    Ask questions, we'll all help best we can.

    Dom
    Dom - TFP Guide
    Intex 18' X 48" Ultra Frame AGP 6700 gallons | Two Intex CS8110 SWG's | Hayward Pro Series 21" Sandfilter | Hayward 1.5HP Power Flo Matrix pump | Hayward Thru-wall Skimmer | Wanda the Whale | 72 sq ft of Sungrabber Solar Panels with Hayward GLC-2P-A | Taylor K2006 Test Kit, Sample Sizer & Speed Stir | Click Here To Become a TFP Supporter!

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    j_m_min's Avatar
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    Re: Bleach question

    How did I determine the algae was gone? I guess I brushed it, shocked it by getting FC up to 20 for a few days and I have been keeping an eye on it. Is there something else to do.

    FC at 6? If I were to do this, I will be pouring in a gallon of 8.25% bleach per day. Is this what you guys are doing? This seems like a lot but if that is what it takes, then I guess that is what it takes. That is $84 a month in just bleach. For example, yesterday instead of putting in half a bottle of bleach I put in a whole bottle. Remember, on a typical day my FC goes from 4 to 2. (I understand you guys think this is low. I will try to beef it up.) So I put in a whole bottle and woke up with my FC at 3. So to keep it at 4 it almost seems if I need to put in more than a whole bottle.

    Maybe I will have to do a CC test and see where I am at in the morning. I will have to do this on saturday as I will be home more and can monitor it.

    As for whatever is in the pool, organics, I get maybe 20 leaves or so in there a day. I run the polaris for an hour or so and it gets them out.

    I have noticed that my DE filter PSI has gone from 12 to 18. Maybe whatever is in my filter is causing some FC loss and I can backwash it.
    25,000 IG plaster pool. DE Pentair 60 gallons. Hayward pump with Single speed AO Smith 2.4 hp motor. Pool installed probably 20 yrs ago. Taylor water tesing kit.

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    Re: Bleach question

    Quote Originally Posted by j_m_min View Post
    How did I determine the algae was gone? I guess I brushed it, shocked it by getting FC up to 20 for a few days and I have been keeping an eye on it. Is there something else to do.

    FC at 6? If I were to do this, I will be pouring in a gallon of 8.25% bleach per day. Is this what you guys are doing? This seems like a lot but if that is what it takes, then I guess that is what it takes. That is $84 a month in just bleach. For example, yesterday instead of putting in half a bottle of bleach I put in a whole bottle. Remember, on a typical day my FC goes from 4 to 2. (I understand you guys think this is low. I will try to beef it up.) So I put in a whole bottle and woke up with my FC at 3. So to keep it at 4 it almost seems if I need to put in more than a whole bottle.

    Maybe I will have to do a CC test and see where I am at in the morning. I will have to do this on saturday as I will be home more and can monitor it.

    As for whatever is in the pool, organics, I get maybe 20 leaves or so in there a day. I run the polaris for an hour or so and it gets them out.

    I have noticed that my DE filter PSI has gone from 12 to 18. Maybe whatever is in my filter is causing some FC loss and I can backwash it.
    As mentioned, you need to read up on how to do a proper SLAM. We don't advocate a random dump of chemicals then guess the algae is gone.

    http://www.troublefreepool.com/conte...tain-shockingl

    2-4ppm of chlorine use is about normal. It's your pool do as you wish, but that $84 a month could turn into 5 times that much if you skimp on the chlorine and let algae bloom.

    Dom
    Dom - TFP Guide
    Intex 18' X 48" Ultra Frame AGP 6700 gallons | Two Intex CS8110 SWG's | Hayward Pro Series 21" Sandfilter | Hayward 1.5HP Power Flo Matrix pump | Hayward Thru-wall Skimmer | Wanda the Whale | 72 sq ft of Sungrabber Solar Panels with Hayward GLC-2P-A | Taylor K2006 Test Kit, Sample Sizer & Speed Stir | Click Here To Become a TFP Supporter!

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    j_m_min's Avatar
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    Re: Bleach question

    Well thanks for the advice. I will keep an eye on it.
    25,000 IG plaster pool. DE Pentair 60 gallons. Hayward pump with Single speed AO Smith 2.4 hp motor. Pool installed probably 20 yrs ago. Taylor water tesing kit.

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