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Thread: algae issue and surface problems

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    algae issue and surface problems

    Bought this house two years ago. The house was built 25 years ago, the pool may be built at the same time or later. I regularly put two 1-pound bags of pool store shocks every two or three weeks and add a block of the 2-inch-diameter-1-inch-thick chlorine granule in the return line container every week.
    The algae became out of control this spring and summer. I found this site and started to read. I thought the problem is too high CYA after reading. I bought the TF100 test kit last week, the following is the test results.
    CYA:250+
    TA: 190
    PH:>8.2
    CH:1250
    Chlorine level: < 0.5
    Before I bought the test kit, I have already suspected that CYA may be too high and I am ready to drain the pool, so I stopped to put more shocks or chlorine granules. I guess that may be the reason of low chlorine level (<0.5ppm).
    Started to drain yesterday, I plan to stop when 5/6 of water is gone. Thus after refill, I will expect that CYA and CH to be ~40 and ~120. I then will do a SLAM after the refill to get rid of algae. Am I right on this plan? The color of the algae is yellowish, is this type very hard to deal with? Should I expect weeks of high FC and brushing when SLAMing the pool?
    While the pool is drained, I think I may be able to do something for the pool surface. As I have noticed that the pool does have scale problem due to too high CH for so many years. I have attached a picture that shows the scale accumulation on the tile surface on the path from the spa to the pool. Can I do something to get rid of this scale while the pool is drained?
    The pool plaster surface may be another issue. I donít know if it is normal for the plaster surface or it is a really serious problem. The surface color is uneven and non-uniform with grey color scattered in dark color. Is this because the last layer of plaster starts to come off or is this because the paining comes off? I canít tell if the surface is colored plaster or painted surface. I have also attached a picture about this. Can I do something about the surface while the pool is drained? Does the surface really need to be re-plastered or can I paint the surface?
    I am not sure if my question makes sense. But thanks so much for help. TG
    20160702_102940.jpg20160702_102907.jpg
    in ground, 18,000 gal, southern CA, plaster surface, DE filter, Hayward SP3400VSP EcoStar, TF100 testkit

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    Re: algae issue and surface problems

    Hi and welcome to TFP

    Your plan for draining to reduce CYA then SLAM seems spot on. I'd always advise caution on draining too much water at once depending on your water table as without the water in it, ground water "could" push it up.

    Im sure someone else here with plaster experience will come along and answer questions as I have no experience in that department.

    Welcome
    18*36*23 true "L" vinyl IG 29,000 gallons. SWG. TF-100 test kit.
    http://tftestkits.net/splash-page.html

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    Re: algae issue and surface problems

    Thanks AimeeH!

    I think I may not need to worry about the ground water. The house is sitting half way on a hill slope and the pool base should be much higher than ground water level. Thanks, TG
    in ground, 18,000 gal, southern CA, plaster surface, DE filter, Hayward SP3400VSP EcoStar, TF100 testkit

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    Re: algae issue and surface problems

    Where are you in California?

    Your pool is a good candidate for an acid wash. Drain the entire thing, clean it up and refill it starting fresh. That pool has been neglected a long time.
    -Brian-
    33K Pool/Spa, Pentair Equipment
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    Davis Custom Construction - Home Page

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    Mod Squad pooldv's Avatar
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    Re: algae issue and surface problems

    Welcome to TFP!

    If the pool plaster is that old then I wouldn't do anything to it. Acid washing is pretty aggressive and could lead to failure of an older finish. There are ways to better manage your water chemistry going forward to prevent future scaling and begin to slowly remove what is there. Although, that is a pretty extreme case of scale. I would drain, kill the algae, refill and then manage the scale.

    Here are some options
    -most aggressive is an acid wash while it is drained
    -next most aggressive is a no drain acid bath following this, The Zero Alkalinity Acid Treatment
    -or best option probably, maintain aggressive water to s l o w l y remove existing scale and prevent any future scale. This is managed through CSI, calculated by Poolmath. Keep it -0.3 to 0 to prevent scale. And keep it -0.8 to -0.6 to try to dissolve scale while brushing with a stainless steel brush. You can also apply dry acid in a sock directly to scale to try to dissolve small areas.

    It is fine to leave it as is and just live with it until it starts leaking more than you can repair. You can also use wet/dry sandpaper to sand down particularly rough spots. It just won't be pretty.

    More about scale here, Pool School - Calcium Scaling
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    Mod Squad pooldv's Avatar
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    Re: algae issue and surface problems

    On further review an acid wash is not such a bad idea while you have the pool drained if you want to do it.
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    Re: algae issue and surface problems

    Thanks pooldv!

    While I need time to read and understand more, I am wondering what is the process of a acid wash. Is it something of a DIY job or is it something that requires hiring professionals?

    For the pool floor, what causes grey area on the dark surface? Is it because that the last plaster layer comes off? I remember I read somewhere that there are several layers of plaster. What is the typical thickness of each plaster layer? I can feel that the gray colored area surface is even with the surrounding dark surface, so it does not like the last layer comes off and it is more like a faded painting.

    Thanks, TG

    - - - Updated - - -

    Thanks bdavis466!

    Orange county in southern California.

    Quote Originally Posted by bdavis466 View Post
    Where are you in California?

    Your pool is a good candidate for an acid wash. Drain the entire thing, clean it up and refill it starting fresh. That pool has been neglected a long time.
    in ground, 18,000 gal, southern CA, plaster surface, DE filter, Hayward SP3400VSP EcoStar, TF100 testkit

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    Mod Squad pooldv's Avatar
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    Re: algae issue and surface problems

    Here is a recent DIY acid wash.
    DIY acid wash on pebble tec pool?
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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: algae issue and surface problems

    I plan to go with option3.

    After the pool is drained to its 1/6-1/8 level, I started to refill the pool this afternoon. I am not sure how long it will take. I plan to do a test after the refill and go from there.

    Is there any procedure I need to follow after refill?

    If the test shows that all the parameters are at the recommended level, that will be an easy task for me. I probably will need to follow the SLAM procedure and kill the algae.

    I'll keep posting progress.

    Have a great 7/4 day! TG

    Quote Originally Posted by pooldv View Post
    Welcome to TFP!

    If the pool plaster is that old then I wouldn't do anything to it. Acid washing is pretty aggressive and could lead to failure of an older finish. There are ways to better manage your water chemistry going forward to prevent future scaling and begin to slowly remove what is there. Although, that is a pretty extreme case of scale. I would drain, kill the algae, refill and then manage the scale.

    Here are some options
    -most aggressive is an acid wash while it is drained
    -next most aggressive is a no drain acid bath following this, The Zero Alkalinity Acid Treatment
    -or best option probably, maintain aggressive water to s l o w l y remove existing scale and prevent any future scale. This is managed through CSI, calculated by Poolmath. Keep it -0.3 to 0 to prevent scale. And keep it -0.8 to -0.6 to try to dissolve scale while brushing with a stainless steel brush. You can also apply dry acid in a sock directly to scale to try to dissolve small areas.

    It is fine to leave it as is and just live with it until it starts leaking more than you can repair. You can also use wet/dry sandpaper to sand down particularly rough spots. It just won't be pretty.

    More about scale here, Pool School - Calcium Scaling
    in ground, 18,000 gal, southern CA, plaster surface, DE filter, Hayward SP3400VSP EcoStar, TF100 testkit

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    Mod Squad pooldv's Avatar
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    Re: algae issue and surface problems

    Ok, first thing to do is SLAM the pool to kill the algae.

    Once you pass the SLAM then enter all your test results into Poolmath and see what your CSI score is. Adjust PH and TA to get it to -0.8. Keep it there and brush the pool with a stainless steel brush as often as you want to.
    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

  11. Back To Top    #11

    Re: algae issue and surface problems

    Not at home on 7/4.

    Finished refill today. Here is the test results.
    1. Chlorine level: <0.5
    2. PH: >8.2
    3. TA: 140
    4. CH: 300
    5: CYA: 30

    Is it possible that PH >8.2 and TA=140 right after refill? Do I need to bring PH to less than 8.2 before I slam the pool? I look up in pool math that to bring the PH form 8.2 to 7.2, I need to add 72 oz of 31.45% MA. Should I go ahead to add the MA? How long should I wait after adding MA to do another test pf PH? Thanks!
    Quote Originally Posted by pooldv View Post
    Ok, first thing to do is SLAM the pool to kill the algae.

    Once you pass the SLAM then enter all your test results into Poolmath and see what your CSI score is. Adjust PH and TA to get it to -0.8. Keep it there and brush the pool with a stainless steel brush as often as you want to.
    in ground, 18,000 gal, southern CA, plaster surface, DE filter, Hayward SP3400VSP EcoStar, TF100 testkit

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    Re: algae issue and surface problems

    Yes, absolutely. That's the makeup of your fill water. Add the acid necessary to lower the ph and that will in turn lower the TA as well.

    Add the acid with the pump running and allow that to circulate for 15 minutes before testing again. It's important to have the PH down around 7 during a slam because the elevated chlorine levels tend to cause false high readings on the pH test. The pH results that you get won't be all that reliable as long as your chlorine level is above 10.
    -Brian-
    33K Pool/Spa, Pentair Equipment
    POOL BUILD
    Davis Custom Construction - Home Page

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    Re: algae issue and surface problems

    Just added 72 oz MA. Should I wait until tomorrow for another PH test?

    Quote Originally Posted by bdavis466 View Post
    Yes, absolutely. That's the makeup of your fill water. Add the acid necessary to lower the ph and that will in turn lower the TA as well.

    Add the acid with the pump running and allow that to circulate for 15 minutes before testing again. It's important to have the PH down around 7 during a slam because the elevated chlorine levels tend to cause false high readings on the pH test. The pH results that you get won't be all that reliable as long as your chlorine level is above 10.
    in ground, 18,000 gal, southern CA, plaster surface, DE filter, Hayward SP3400VSP EcoStar, TF100 testkit

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    Mod Squad pooldv's Avatar
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    Re: algae issue and surface problems

    Yes, verify that PH reached 7.2 and held.
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  15. Back To Top    #15

    Re: algae issue and surface problems

    After adding MA and aeration and adding more MA, ph and TA are now ~7.2 and ~100. CH is 300 and CL is less than 0.5.

    But I found that my first time CYA test may be not accurate, it is more likely to be less than 20 instead of 30. What to do next? Should I add stabilizer to bring CYA to 30ish? Or Should I go ahead to slam the pool?
    If I need to add stabilizer, do I need to wait one more day for CYA level to be stabilized?

    Thanks!

    Quote Originally Posted by pooldv View Post
    Yes, verify that PH reached 7.2 and held.
    in ground, 18,000 gal, southern CA, plaster surface, DE filter, Hayward SP3400VSP EcoStar, TF100 testkit

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