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Thread: New Pool Owner with Algae

  1. #1
    Join Date
    Jun 2018

    Default New Pool Owner with Algae

    Newbie Here! First off, let me say that these forums have been immensely helpful so far in starting to understand the basics of pool ownership and maintenance. So thank you to all of the people running this and contributors.

    So I bought the Taylor K2006 test kit and did my levels for the first time. Since the beginning of the season I have been throwing a bunch of cal hypo shock in once a week based on instructions from my pool guy. I want to stop screwing around and do this right with BBB.

    The pool is 30,000 gallon, in ground, concrete pool. It gets direct sunlight for about 6 hours a day. There is a auto chlorinating basket (set to level 5) that I am using with the chlorine tabs (hockey pucks) as well. The water is reasonably clear right now but I am getting green algea buildup on the walls that get the most sun exposure.

    FC = 2.2 ppm
    Combined Chlorine - very slight pink hue
    PH = ~8 (two drops to get down to 7.4)
    Alk = 160
    Cal = 200
    CYA = NA (confused because the black dot never disappeared. not sure if I did something wrong here but I did the test twice and could always see it)

    Any advice would really be appreciated! Thank you!

  2. #2
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    Default Re: New Pool Owner with Algae



    1. Back off on the cal hypo shock. Your calcium is moving right on up there.

    2. Sometimes the CYA test needs to 'develop'. Retest, and after mixing, let the solution sit for 120 seconds before 'measuring'.

    3. If your CYA is really 0 (test solution is clear, not cloudy) or lower than 20 ppm (solution is not cloudy enough to make the dot disappear . . . then you need some. The EASIEST way to add CYA is to use dichlor as shock, instead of cal hypo (55% chlorine, 50% CYA . . . and yes, I know those %'s don't add up. Long story .) You can get 24x 1# bags of shock at the Sams Club in Secaucus OR you can get it from Amazon, almost as cheaply: Option #1, #2, #3. Watch prices and quantities at Amazon. Currently (June 2018) the #1 option is best.

    4. Your "Pool Factor" is 4, so 24# of dichlor will add about (4 x 24 x 0.55) ppm of CYA, or 53 ppm . . . which is about right.

    5. Read the muriatic safety page, linked in my signature. Then, use muriatic acid to lower your pH to the 7.2 - 7.8 range. Once you've done so, recheck alkalinity.

    6. Without a specific reason to do so, do NOT add any more calcium, alkalinity ("sodium hydrogen carbonate" or baking soda), algaecide, etc.

    7. Take a look in the tank of the oldest toilet in your house. Gray or tan interior = no metals in the fill water; dark orange or orange-brown means iron. Unless the tank interior is metal-free, ALWAYS add fill-water SLOWLY via the skimmer with the PUMP RUNNING. It's a good idea to do so with a trichlor tab in the skimmer as well. The chlorine tends to push any dissolved metals into an insoluble, filterable form. [ There's an even better way, involving your cal hypo shock, but ONLY if you have a sand filter. ]

    8. Welcome to my lab, prospective guinea pig! " Green algae buildup on the walls that get the most sun exposure" is almost always mustard algae, the most difficult form of algae to resolve. For now, keep your chlorine up. The BEST way -- for now, given your existing chemistry -- is to pour 10% pool bleach over it, each evening. This stuff, Pool Essentials Chlorinating Liquid is available at the Suffern Walmart in aisle Y.7 for $3.64/gal. Get about 10 gallons. Add one EACH evening in the location of the algae, and then brush the algae.


    OK. That's standard. Here's the 'guinea pig' part: there's no good standard way to deal with mustard algae. It's tolerant of VERY high levels of chlorine. Copper algaecides work, but only at levels that will stain your pool, and turn light hair green. Monochloramine (Yellow Out) works, but it's a devil's bargain, with horrible side-effects. Other algaecides simply don't work.

    What does work, is phosphate removal treatment (PRT) . . . but NOT the way pool stores do it. In the past, we've specifically recommended against attempting PRT, because it didn't work. However, over the last few years, I've established that it DOES work, very well indeed, IF you do it right. In fact, I suspect that mustard algae, this early in the season either means you've been using phosphate based stain/scale products (most are!) OR you have high phosphates in your fill water.

    The first step is to test BOTH fill water AND tap water. If you decide to go ahead, even without testing, order 3 quarts of PR10000. This is probably your BEST option, but you need to understand that
    1. Phosphates will be present BOTH in your water, and in your system (including plaster). It may take 3 weeks to get to the point where you can sustain a low phosphate level.
    2. If your pool leaks AND if your fill water contains a lot of phosphates, THEN PRT may be expensive. Only testing will tell that. Otherwise, it should save money.
    3. A little phosphate removal is COMPLETELY useless. As Yoda said, "Do. Or do not. There is no try!". You can lower phosphates from 3,000 ppb (3 ppm) to 200 ppb (0.2 ppm) . . . and your mustard algae will continue to grow. The target is maintaining phosphates near or below 50 ppb (0.05 ppm).
    4. It's a process. Even after you've removed all residual phosphates, they will continue to 'appear' from leaves, swimmer sweat or urine, and fill water. You'll need to add a small amount of product every week (or perhaps, 2 weeks).
    5. Phosphate removal will temporarily cloud your water. I found it was unnoticeable IF I could make additions at night. But depending on your filter, pump run time, and more it may be necessary to work out a process that avoids cloudy water, especially during the initial cleanup.

    OK. Those are the requirements and gotchas. Here's the good stuff:
    1. Once you are sustaining low phosphate levels, algae growth will be VERY slow, and chlorine will be able to EASILY kill it.
    2. Going on vacation should be a snap. Just add an extra dose of remover, to soak up any phosphate that 'appears', shock the pool, and take off!
    3. Chlorine consumption will be reduced. My testing was on large commercial pools, which has different requirements, but I suspect that, once the phosphates are stable, at low levels, simply shocking weekly may be ALL that's needed.


    Taylor K-1106 phosphate
    Phosphate remover:
    Orenda PR10000
    Eliminating Algae from your Pool
    Recognizing and Treating Algae

  3. #3
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    Default Re: New Pool Owner with Algae

    [ Upgraded membership; moved thread to "Algae" section <= you may need to log out and back in, before you can see everything. ]

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