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Thread: Killing yellow algae

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    j_m_min's Avatar
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    Killing yellow algae

    OK guys. I am changing this portion of my pool care to this thread as it no longer has to do with the electrical usage of my pump.

    I tested my water for the first time and I got:

    OK guys. I am ready to get serious about getting rid of this yellow algae as the weather in houston is warming up.

    I used my test kit and here are my numbers. How bad am I?

    Free Chlorine = 2.4
    Combined Chlorine = .6
    PH 7.1
    -in the book table to raise PH it says if your base demand test took 10 drops for a 20,000 gallon pool to use 6.4 pounds of soda ash. My pool is 25,000 gallons and took 12 drops.

    My alkalinity is 120

    My calcium is 870

    My cyanuric acid I couldn't even read because the water got too cloudy before I got to the numbers on the side of the tester. at the 1.8 fill line I couldn't see the dot. at the 4.5 fill line the reading was 80. Not sure what this means.

    I tested my cyanuric acid with half tap water and half pool water and it was still over 100. My Taylor tester only goes to 100.

    I am currently draining my pool. I think I am just going to drain it all, unless for some reason I shouldn't.

    I have heard of people doing an "acid wash" on the pool, before filling it. I haven't done research on that yet. Just wondering what the thoughts are on doing this before filling it.

    Also, I have places in my plaster where the white is gone and you can see the darker material underneath. I don't know if this was from having the cyanuric acid level so high and brushing it. I know during regular brushing that I would see whitish powder come off in the water. You can see the bare spots in the pictures attached. Is there any reason I should be concerned about these areas where the white plaster is gone? besides cosmetic reasons. Do I need to get some plaster guy to fix this before I fill it up. I don't think the pool has any links. Here is a picture of my pool from the winter, here are two pictures of what it looks like mostly drained. I brushed it pretty good yesterday, that is why you can kind of see algae streaks on the walls.
    Attached Images Attached Images
    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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    j_m_min's Avatar
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    Re: Killing yellow algae

    Maybe acid wash is the wrong term. DO I need to bleach the walls and scrub them first, or can I just fill it and SLAM 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: Killing yellow algae

    Choice is yours, but if you scrubbed with dilute bleach/water it would certainly help. If it were me, and I'd already drained that's what I would do. Which Taylor kit do you have? You'll need a FAS DPD FC test to Slam once you are full.
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    Re: Killing yellow algae

    My taylor kit was $60. It tests free chlorine, combined clorine, PH, alkalinity, cyanuric acid and ? I can't remember. THink it does 5 tests. WHat is FAS DPD FC stand for?

    How much bleach vs. water do you use?

    Any reasons to be concerned about the worn off plaster?
    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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    j_m_min's Avatar
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    Re: Killing yellow algae

    ALso, should I not drain the whole pool to keep my CYA levels up as much as possible? How fast do the tablets replace CYA?
    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: Killing yellow algae

    I think I would not drain further and start the refill/cleanup process. Clorox the walls.....I think that will remove a lot of those runny looking stains.

    While you are doing that, you shouldread "The ABC's of Pool Water Chemistry" up in Pool School. You have to gain a better knowledge of the basics so you can go forward with your SLAM.
    Dave S.
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    Re: Killing yellow algae

    Quote Originally Posted by j_m_min View Post
    My taylor kit was $60. It tests free chlorine, combined clorine, PH, alkalinity, cyanuric acid and ? I can't remember. THink it does 5 tests. WHat is FAS DPD FC stand for?

    How much bleach vs. water do you use?

    Any reasons to be concerned about the worn off plaster?
    A 60/40 water to bleach is more than adequate, and 80/20 would work as well. You can limp by on the plaster, but if it starts getting worse, plan on re plaster next year.

    The FAS/DPD Chlorine kit is a high range Free Chlorine (FC) Test. If you add powder, it turns pink, then add drops until it's clear to test your FC the. That's what you have. A Taylor k2006 kit has this test. If you don't have that, you'll need one to SLAM.

    +1 on the Pool School...ABCs first. Ask all the questions you need too, we are glad to help.
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    Re: Killing yellow algae

    Thanks guys. I am gong to bleach the walls and then fill it up. I understand that I need to monitor my chlorine carefully. I will be at work during the day so I will do my best.

    I have the Taylor k2006 kit.

    I drained the pool a lot. So I assume my CYA is going to be really low. WIll adding chlorine tablets bring this up or do I need to do some shopping to get it up to 25 ppm?

    Is there a thread to follow about how to get "new" water up to quality ASAP? I have no idea my chemical readings for straight tap water (houston city water)

    I went to LEslie pool supply to price their liquid chlorine $17 for 4 gallons, and they told me that next week they are getting in a chemical that lowers CYA? Have you heard of this?

    - - - Updated - - -

    ALso on the plaster, how do I know when I need to do something about it? Outside of a leak, what are the downsides of old plaster? Can it hurt anything? will it cause the pool to leak faster? I assume there is concrete under the plaster.
    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: Killing yellow algae

    You start by getting a complete set of water test results from a reliable test kit. What you do from there varies a great deal depending on what your levels are. Post some test results and we can give you specific advice.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Killing yellow algae

    You may have enough Cya, or at least some to work with for a SLAM procedure once re-filled. Let's wait on being full to re test that. If you don't have enough for Slam, we will advise you buy some small amount, but again, let's wait till full and tested.

    Good move on the liquid Chlorine, you'll need plenty.

    We are watching details on the Cya reducer, but the jury is still out on that. Way too early to tell anything on that yet.
    While not good, you won't leak with the plaster as is.
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    Re: Killing yellow algae

    Filled my pool up over 2.5 days with hose. My cya was off the charts prob 200. Redid test

    Fc went from 2.4 to .4. This .4 comes from me putting 8 gallons of liquid chlorine 10% into the pool went is dropped it all over the sides of the pool on Monday night.

    Cc went from .6 to .2. Water was barely pink.

    Ph went from 7.1 to 7.4

    Alkalinity went from 120 to 140

    Calcium went from 870 to 140

    Cya went from 200 to zero. Filled tube all way up and no cloudiness.

    I know I need to get fc up and cya to 25.

    Any recommendations on my next step?

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    Re: Killing yellow algae

    I have trichlor pucks and cal hypo granual shock

    - - - Updated - - -

    Do I need to slam it as I just drained it and poured 8 gallons of liquid chlorine all over the walls? Pool is super clear of algae right now

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    Re: Killing yellow algae

    It will take awhile to get the CYA up,with the pucks. I believe each puck adds like 6-9 ppm CYA. You can pick up stabilizer/conditioner at Wal-Mart or Lowe's n use that. Be careful,using the Cal hypo as you don't want to get it back up to high as it was. You're already at 140ppm. You can SLAM to 10ppm right now but you'll lose that once the Sun comes up until you get CYA in the pool.
    I'd bet you my bikini you'll never get TFP water from a pool store!

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    Re: Killing yellow algae

    Casey has you right. Buy a little Cya, take it to 30-40. Way better to add than subtract CYA. Before you buy Calcium, let's see what's in your makeup. Run a CH on the fill water when you have some time.

    Get the Cya, and a bunch of Bleach, and check back. We will walk you through if you need some help, just ask before adding if you have questions. Have you checked out the SLAM procedure? Link is in my signature, but it's a good idea to review it.
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    Re: Killing yellow algae

    OK, it has been 10 days. I bought one gallone of liquid CYA. I poured it in the pool. Because I was going out of town for 3 days, I put 6 trichlor pucks in the skimmer basket, 4 in the floating shark, and 8 were already in the chlorinator.

    Pool chlorine is still over 5. (I figured I was wasting test drops by going any further)
    CYA is up around 35.
    PH dropped to about 7.1.

    I think I put too much chlorine at once, but the pool looks super clear.

    The one gallon of liquid stabilzer said that it would take 10,000 gallons to 30 cya. I figured since my pool is closer to 25,000 gallons that it would take me to 10-15 cya. What concerns me is that means that I gained 20 cya from 6-10 pucks? If I continue to chlorinate with the pucks, my cya is going to be off the charts in no time. I understand that you guys recommend liquid chlorine, but what I don't understand is how this product, pucks, is so popular for people to use, but it takes the cya over recommended levels. How does anyone use this product or recommend it? If I understand correctly, anyone who uses pucks will eventually in one summer have such high cya that their chlorine is ineffective? Maybe this works in cities where you drain the pool in the winter.

    Do they make pucks that don't have the stabilizer? Some times I am not at home for 5-7 days because of work and I don't have time to dump liquid in.

    If you do liquid, how do you know how much to dump in? Trial and error?

    My pool is algae free and I really really want to keep it that way.

    I guess I am not sure if there is anything I should do now beside sit back and monitor the levels.
    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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    Mod Squad pooldv's Avatar
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    Re: Killing yellow algae

    No, there are no solid forms of chlorine without CYA in them.

    Use PoolMath to determine how much to add.

    All that is required to keep the pool algae free is to maintain FC above the min level indicated here Chlorine CYA Chart. You can go up to shock level for a trip. Daily testing will help you understand your approximate daily burn rate.

    Well, FC and the rest of the Recommended Levels. But, FC is key.
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    j_m_min's Avatar
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    Re: Killing yellow algae

    This sucks but I will do what I can. I travel a lot, like 5 days at a time. The tablets are nice but I do not want to risk algae all over again. Thanks for all the help.
    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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    Mod Squad pooldv's Avatar
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    Re: Killing yellow algae

    There are other options for adding chlorine to the pool. Stenner pump and liquidator for adding liquid chlorine/bleach and saltwater chlorine generator are all commonly used here at TFP.
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