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Thread: algae in a saltwater pool

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    algae in a saltwater pool

    I think I have algae in my pool. I switched to saltwater this season thinking that I wouldn't get algae. There is brown stuff one side of the pool and the other side is fine. The water is alittle cloudy but still clear. Last yr when I had algae, the pool was green and you couldn't see the bottom. Could it be algae or just dirt?

    Heres my current test:
    FC 6
    CC .5
    TC 2
    pH 7.2
    T/A 80
    CH 150
    CYA 70
    18' Willow round AG 52", 19" Sand filter 1 hp pump, Intex SWG 8110, Bought and install May 08
    New 12'x16' deck built March 09
    Poss thinking about solar panels next!

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    frustratedpoolmom's Avatar
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    Re: algae in a saltwater pool

    You're TC can't be 2 if your FC is 6

    Tonight, turn off the SWG before you go to bed, and do an Overnight Loss test. If you lose more than 1ppm, then you likely have an algae issue. If your FC holds overnight this isn't algae, just dirt or pollen or something.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
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    Mod Squad Bama Rambler's Avatar
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    Re: algae in a saltwater pool

    I was about to write the same thing about the TC but of course FPM beat me to it.

    You also need to bring your pH up a bit too. Aeration is the best way but it takes a while.

    We live near a dirt road and constantly battle dirt. If it's not sticking to the walls it probably dirt. I'd strongly suggest doing the overnight drop test FPM suggested to be sure though.
    Dave J. TFP Moderator
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    Re: algae in a saltwater pool

    sorry about the tc. i meant 6.5. anyways i just went outside and there is some on the wall. should i shock the pool or just do the overnight test?
    18' Willow round AG 52", 19" Sand filter 1 hp pump, Intex SWG 8110, Bought and install May 08
    New 12'x16' deck built March 09
    Poss thinking about solar panels next!

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    frustratedpoolmom's Avatar
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    Re: algae in a saltwater pool

    You see a visible patch growing on the wall? Yikes. That and the "slightly cloudy" water, you probably have to shock. Your FC is high enough you shouldn't be getting algae....

    Did you supplement the SWG with bleach, or is that your normal level? (Do you always stay above the "min"?
    How often are you running your pump?
    Do you have any areas of poor circulation like wedding-cake steps or light niches where algae can hide?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
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    Re: algae in a saltwater pool

    i have the swg run for 4 hours at night and the pump is ran 8 hrs. where the brown stuff is, that part of the pool is in the shade most of the day the side that gets the sun is completely clear. i havent shocked the pool since i opened it since the FC has been around 6-7. i thought that was a little high so i turned the swg down to 3 hours and then this happened. when i brush it the stuff comes right off and makes the water more cloudy but then goes back to normal within a min. its not slimy or anything, it doesn't feel like anything. we have a normal pool ladder.
    18' Willow round AG 52", 19" Sand filter 1 hp pump, Intex SWG 8110, Bought and install May 08
    New 12'x16' deck built March 09
    Poss thinking about solar panels next!

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    Re: algae in a saltwater pool

    I have the intex swg as well...what I can tell you has worked for me is to follow the CYA/Chlorine recomendation for a non-swg pool. The reason I say this is that I too only have a 3-4 hour SWG run time with and 8hr pump run time and in my opinion the SWG does not "mini-shock" long enough or one complete turn-over of my water...so I just keep the FC as per the bleach recommendation. That has worked for me.

    I would perform the overnight test as that will tell you if you need to shock. Your getting good advice so far.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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    Re: algae in a saltwater pool

    I'd strongly recommend that you add 50 ppm Borate(I used 20 MuleTeam Borax), your ph/TA is low enough to do it fairly easily, and it is pretty good as a permanent mild algaecide, plus it helps lock in ph. I'd use the pool calc to look up the amount for you, but once I start to post a reply, it takes the sigs off of the bottom and I can't see your pool size! I used 18.6 boxes in my 24k pool(and ~4 gal of MA) which is still cheaper than a gallon of 60% poly-quat algaecide at Leslie's, and it is a one time deal.
    22 x 40 IG vinyl lined, 23,570 gal.
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    Re: algae in a saltwater pool

    Quote Originally Posted by Bama Rambler
    You also need to bring your pH up a bit too. Aeration is the best way but it takes a while.
    Why? pH of 7.2 is within range and the pH in a salt pool will rise on it's own.

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    Re: algae in a saltwater pool

    here are some pics of the pool



    18' Willow round AG 52", 19" Sand filter 1 hp pump, Intex SWG 8110, Bought and install May 08
    New 12'x16' deck built March 09
    Poss thinking about solar panels next!

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    Re: algae in a saltwater pool

    now that i have really looked at what mustard algae is, i realize that i have it. so i was thinking of doing 24 hrs shocking the pool at 40.5 (if i read the chart right), then i have to add the stuff for the algae right? also how would adding borax affected my dogs, they love to go swimming and do drink some of the water while swimming?
    18' Willow round AG 52", 19" Sand filter 1 hp pump, Intex SWG 8110, Bought and install May 08
    New 12'x16' deck built March 09
    Poss thinking about solar panels next!

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    frustratedpoolmom's Avatar
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    Re: algae in a saltwater pool

    Borates and your dogs are an issue.

    Have you see this thread:
    http://www.troublefreepool.com/high-...ae-t16376.html

    The pics are confusing, I can't tell what I'm looking at, the lighter blue is the wall or the floor? That does indeed look like algae.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: algae in a saltwater pool

    Quote Originally Posted by dmanb2b
    I have the intex swg as well...what I can tell you has worked for me is to follow the CYA/Chlorine recomendation for a non-swg pool. The reason I say this is that I too only have a 3-4 hour SWG run time with and 8hr pump run time and in my opinion the SWG does not "mini-shock" long enough or one complete turn-over of my water...so I just keep the FC as per the bleach recommendation. That has worked for me.

    I would perform the overnight test as that will tell you if you need to shock. Your getting good advice so far.
    THIS is the best advice in this thread. Follow it once you kill the algae. It looks like mustard algae to me.

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    Re: algae in a saltwater pool

    Thanks Waterbear!...Again I know Pool School contains general recommendations, but if there is any truth to my theory, perhaps we could ask Jason to add a footnote to the chart, since it looks like more and more cheap folks like me are trying out the Intex SWG.

    I realize it's such a no-frills SWG, but it is a powerful little SWG and must just run at 100% when it does run. So my thinking was that although it shocks the heck out of the water that does run through it in 3-4 hours, it's not the same with all my water on a daily basis...so hence to be safe I just pretend I'm still lugging bleach bottles and follow the non-swg recommendation. Similar to bleach additions which happen once or twice per day using bleach...my SWG only generates chlorine for max 4hrs and then nothing is being added for 16 hours.

    I thought the SWG suggested levels we designed to be more in line with the fact that higher-end models generate smaller amounts of chlorine over a longer period of time, therefore inhibiting algae growth, despite the lower suggested FC level.

    Hope that all makes sense.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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    Re: algae in a saltwater pool

    Quote Originally Posted by dmanb2b
    Thanks Waterbear!...Again I know Pool School contains general recommendations, but if there is any truth to my theory, perhaps we could ask Jason to add a footnote to the chart, since it looks like more and more cheap folks like me are trying out the Intex SWG.

    I realize it's such a no-frills SWG, but it is a powerful little SWG and must just run at 100% when it does run. So my thinking was that although it shocks the heck out of the water that does run through it in 3-4 hours, it's not the same with all my water on a daily basis...so hence to be safe I just pretend I'm still lugging bleach bottles and follow the non-swg recommendation. Similar to bleach additions which happen once or twice per day using bleach...my SWG only generates chlorine for max 4hrs and then nothing is being added for 16 hours.

    I thought the SWG suggested levels we designed to be more in line with the fact that higher-end models generate smaller amounts of chlorine over a longer period of time, therefore inhibiting algae growth, despite the lower suggested FC level.

    Hope that all makes sense.
    Perfect sense and I think you have it worked out exactly right! One of the benefits of a "standard" SWG which is shared with such devices as peristaltic pumps and the liquidator is the constant (or al most constant) dispensing of very small amounts of chlorine during pump run time. The intex SWG does not do this so it is more akin to manually chlorinating, IMHO. You get what you pay for.

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    Re: algae in a saltwater pool

    Hmmmm...I thought the higher end SWCG's performed basically the same as the Intex, but did it as a percentage of a 24 hour day, instead of # of hours like the Intex. So, if you had one of the big boys set at 20%, then it ran at 100% generation for 20% of a 24 hour cycle (or 4.8 hours), and then shut off until 24 hours later.
    24' x 52" AGP - approx 13,500 gallons
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    Re: algae in a saltwater pool

    The first picture was of the wall and second of the floor. I turned off the swg and did an overnight test and lost 6. So I added more shock this am and will check the level when I get home from work. I picked up algaecide from the pool store (it worked last year) when do I add that? Do I wait for the pool to stop losing fc? I'm having a party on the 31st do u think the pool will be ready by then?
    18' Willow round AG 52", 19" Sand filter 1 hp pump, Intex SWG 8110, Bought and install May 08
    New 12'x16' deck built March 09
    Poss thinking about solar panels next!

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    dmanb2b's Avatar
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    Re: algae in a saltwater pool

    return the algaecide to the store and continue shocking the pool as described in pool school. If you follow those directions, there is no reason you can not be ready for your party
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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  19. Back To Top    #19

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    Re: algae in a saltwater pool

    So I don't have to use any algaecide? Just keep shocking until I lose less than 1 overnight?

    Can you return it to the store or do they say no?
    18' Willow round AG 52", 19" Sand filter 1 hp pump, Intex SWG 8110, Bought and install May 08
    New 12'x16' deck built March 09
    Poss thinking about solar panels next!

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    frustratedpoolmom's Avatar
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    Re: algae in a saltwater pool

    Depends on the store - some will take it back, some won't.

    Keep shocking, brushing and filter run 24/7 until the FC holds, and then raise it up for 1-2 days to the Mustard Algae shock level, and then for the next month maintain the Mustard Algae "min" shown here:
    http://www.troublefreepool.com/chlor...art-t2346.html

    Make sure you brush everything and throw the pool toys in the pool while at shock level so they get treated too, wash all suits and towels, etc.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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