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Thread: Still green algae - chlorine off the charts - algaecide?

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    Still green algae - chlorine off the charts - algaecide?

    Hello. I am new to these boards as I have just purchased a house with a pool but I have been reading through Pool School and trying to get on top of things.

    I have a 20,000 gallon in-ground pool/spa with a main drain and two skimmers and then a fountain return in the spa and a couple of return jets in the pool. I have a DE filter and an in-line tablet chlorinator.

    I took my water in to get tested last weekend and was given the following test results:

    Free Chlorine - 0
    Total Available Chlorine - 0
    Calcium hardness - 200
    Cyanuric Acid - 30
    Total Alkalinity - 60
    pH - 7.6

    So I dumped 11 pounds of baking soda into the pool to fix my alkalinity and backwashed the filter and put in 7 lbs of DE. Apparently I had forgotten to reload the chlorine tablets so that's why there was no chlorine. So loaded the feeder up with tablets and ran it all week for 8 hours a day.

    Then this weekend I went in and got these results:

    Free Chlorine - 0
    Total Available Chlorine - 0
    Calcium Hardness - 200 ppm
    Cyanuric Acid - 40
    Total Alkalinity - 80
    pH - 7.6

    Which is surprising since I had the feeder running with the valve turned to 5. So then I shocked the pool with 2 pounds of power powder from Leslie's Saturday afternoon and the pumps been running for about 24 hours now. I brushed the **** out of the pool before I shocked it and there were loads of clouds of green algae.

    Now I just tested it with my home kit and the chlorine level is off the charts - way above 3ppm, the pH is 7.4 and the alkalinity is around 70. But there are still a lot of green clouds on the bottom of the pool and on the walls and skimmer mouths. The guy at Leslie's told me to shock the pool, run the pump for 24-48 hours and then use algaecide but I gather from these boards that algaecide is seen as a bit of a scam.

    Any ideas on what I should do to get this pool sparkingly clear again? I have the shock, I have some stabilizier/conditioner (which I believe is cyanuric acid) and I have the algaecide. And I have the phosphate free stuff that he sold me a few weeks ago. Yes, I realize I am putting the Leslie's Pool guy's kids through college.

    Can someone give me some direction here?

    Also, I'm having a lot of trouble with stuff on the surface of the water. Either due to jet placement/strength or lack of skimmer suction, it just sort of gathers on one side of the pool but doesn't suck into the in-ground skimmers. I turned off the main drain for a while as per the advice of someone I saw on this board and that helped a little but it didn't do a ton. I have little jet-like things that aren't jets under each skimmer mouth - are they supposed to be doing something? Sucking? Blowing? Because they are doing neither. The water's definitely going into the skimmer and it's spinning around like it's going down the drain but I just feel like there can't possibly be this much leaves and berries and dead bugs that are supposed to float on the surface.

    Also, perhaps the answer is that i need to upgrade/fix my pool cleaning robot. It's a Polaris but it must be 15 years old and I sense that it is not as good as it used to be. It stops a lot and when the cord to it gets tangled up it shuts down. Anyone have a great recommendation for a new robot that's not a fortune?

    Sorry for the bombardment of questions. I live in Dallas and it's going to be over 100 every day for the next four months so I want to have this thing under control by the time summer really hits.

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Still green algae - chlorine off the charts - algaecide?

    Welcome to TFP!

    It sounds like you aren't using nearly enough chlorine. 2 lbs of Power Powder Pro would raise the FC level by about 7, while shock level for your CYA level is around 15.

    Now might be a good time to do some reading in Pool School, particularly the chapter on how to shock your pool.

    What kind of test kit do you have at home?
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Still green algae - chlorine off the charts - algaecide?

    I have the Basic 5 Test Kit. ... 22260.html

    I suppose I should invest in the FAS-DPD test.

    I see on the CYA chart that I want the FC at 16 for shock. The pool calculator tells me that's 2.9 lbs (47 oz) of Cal Hypo so I can add another pound of the Power Powder Plus. The problem, of course, is that my test doesn't read FC above 4ppm so I won't be able to determine whether it's staying at shock level of FC. I will order the FAS-DPD test and then follow the steps in Turning Your Green Swamp Back Into a Sparkly Oasis.

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    Join Date
    May 2011
    Clearwater, FL.

    Re: Still green algae - chlorine off the charts - algaecide?

    Hi pokey and welcome to TFP!
    Jason nailed it, your not hitting your shock level to ever kill the algae faster than it can grow, all you doing is wasting time, chlorine and shock by not understanding the right process.
    1st thing is you need a professional test kit so you can test your own pool yourself, not relying on pool store testing as they can not be correct most of the time. Your own test kit is the only way to go. The bigger advantage is you can test anytime you need to.
    MY recommendation is the TF-100, great value and is high quality.
    Continue to read the chapters in pool school on instructions for shocking your pool. It's a process of using the CYA/Chlorine chart for your level of shock
    See here:
    Use the pool calculator to add the proper amounts of chlorine here:
    Your goal in the shocking process is to never let your FC level fall behind the algae using it up faster than your killing it, especially in the beginning.

    Swim n Play 21' round, expandable 72" liner, 6FT deep center, buried 14", 12,750 Gallons
    Waterway 1HP-2 speed with 22" Sand filter
    TF-100 test kit
    Thanks to TFP my pool is perfect all the time :party:
    I now suffer from Sparklypoolitis! :whoot:
    I am a Platinum contributor because I want everyone who comes here to Trouble Free Pool to have the same success that I enjoy with my pool and family.

  5. Back To Top    #5

    Join Date
    Feb 2008
    Denton, TX

    Re: Still green algae - chlorine off the charts - algaecide?

    If you shock properly, it should take 2 to 3 days to get your water clear here in DFW. A FC of 3 ppm is not off the charts. It's barely making it on the charts. There are two things you need to get going. Number one, a good test kit. This is a test kit that has a FAS-DPD test for chlorine. You can't shock properly untuil you can test FC higher than 5 and the FAS-DPD test is the only chlorine test for the consumer level that can do this.. Please go to and purchase either the TF-100 or the Taylor K-2006. Number two, you need to understand the process of shocking. Please read pool-school/shocking_your_pool so you can understand how to go about it.

    If you do these things, your pool will clear quickly.

  6. Back To Top    #6

    Re: Still green algae - chlorine off the charts - algaecide?

    Thanks guys, this is great advice. I will get the kit and follow the shocking steps. It sounds like everyone agrees liquid bleach is the way to go. I have the puck feeder, can I keep using that generally and use liquid bleach for shocking as per the pool school instructions? Or will the increasing CYA be disastrous?

  7. Back To Top    #7

    Join Date
    Feb 2008
    Denton, TX

    Re: Still green algae - chlorine off the charts - algaecide?

    As long as you understand that using the trichlor tablets will continuously raise your CYA over time, your understand the problems with high CYA, and you take steps to prevent the CYA from accumulating levels that can cause problems, you can use the tablets. We tell most folks that if they aren't willing to change out water regularly, then they should switch to unstabilized forms of chlorine once their CYA gets to the upper limits (around 50 ppm).

    ETA: And yes, as long as you are shocking, I would avoid the tablets and just stick with bleach. Makes it easier.

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