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Thread: algae and phosphates

  1. #1
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    algae and phosphates

    Split from recurring-algae-problem-t69257.html Butterfly

    Parkerman - What is your phosphate level in the pool?
    If you don't know, take a sample down to your local pool supply store as they usually will test the sample for free. If your phosphate level is high, you will have to remove it with a 2 part treatment that draws the phosphate out into a precipitate which the filter then filters out of the water.
    You will then need to disassemble your DE filter, as backwashing your filter is not sufficient, by removing the filter elements, removing all of the DE from the elements, then cleaning everything with a diluted solution of muriatic acid. Replace any damaged or torn elements. Reassemble all elements by placing a small amount of silicon on the plastic portion of the filter elements where they attach to the manifold. This will prevent them from becoming frozen together and make disassembly easy the next time they have to be removed.
    Test the water again to ensure that phosphate levels are near zero.
    Phosphates are food for algae and no matter how much algaecide (Polyquat) you put in the pool, you will not be able to stop or control the algae. Phosphates are commonly found in anti-staining chemicals/treatments as well as organic material (leaves, sweat, grass) that ends up in the water.
    And yes, regular brushing does aid in preventing algae from taking hold on surfaces, but if your pool chemistry is not right (Phosphates included) no amount of brushing will prevent it.
    This should resolve your problem.
    20K IG SW White Plaster Pool & Jacuzzi -2 HP Hayward EcoStar Pump - 70ft2 150GPM Hayward Pro-Grid D.E. Filter DE6020, Hayward AquaRite SWG Auto-Chlorinator with 25,000 gal Turbo Cell, TF100 Test Kit
    Laguna Niguel, CA

  2. #2
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    Re: recurring algae problem

    Quote Originally Posted by duraleigh
    parkerman,

    Welcome to the forum. Algae establishes in pools that have inadequate chlorine....period. Rather than dwell on how your algae got started, I would get rid of it. You get rid of it by SLAMming the pool per the article in Pool School. Brush, vacuum and run your pump 24/7 during the process.

    While your test results look fine, just keep in mind that the algae is in your pool because your chlorine has been inadequate....no other reason.

    Follow the SLAM process correctly and the algae will go away. It will only reoccur if you allow the chlorine to fall too low and/or fail to practice good maintenance technique like vacuuming, brushing, etc.

    Mark92677,

    Controlling phosphates are a completely unnecessary part of pool water management. Thousands of us here on the forum never test for them and never will. Google "phosphates" here on the forum and read more about the logic behind ignoring them.
    I am not sure why you believe that phosphates have no effect on algae growth. Our senior chemist at B. Braun Medical (Manufacturer of IV solutions) disagrees to the contrary and referred me to many studies performed proving the phosphate/algae relationship.
    One of the studies (Nitrate and phosphate levels positively affect the growth of algae species found in Perry Pond., STEFFII FRIED, BRENDAN MACKIE, and ERIN NOTHWEHR, Biology Department, Grinnell College, Grinnell, IA 50112, USA) he referred to states,
    "As expected, nitrate and phosphate levels both significantly affected algal growth. These results are supported by Ryan et al. (1972), Frink and Machlis (1968), and Sikka and Pramer (1968) who found that both nitrate and phosphate levels have a significant effect on algae growth."

    In my instance, I was having uncontrolled algae problems that could not be controlled by the methods that you are recommending. It wasn't until I brought the phosphate level down to 300 and cleaned the DE filter in the manner I suggested, that conventional pool chemistry could then control the issue.

    This senior chemist oversees all water testing, filtration, distillation, and polishing to produce water that meets USP WFI requirements for use in IV solutions.
    20K IG SW White Plaster Pool & Jacuzzi -2 HP Hayward EcoStar Pump - 70ft2 150GPM Hayward Pro-Grid D.E. Filter DE6020, Hayward AquaRite SWG Auto-Chlorinator with 25,000 gal Turbo Cell, TF100 Test Kit
    Laguna Niguel, CA

  3. #3
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    Re: recurring algae problem

    I am not sure why you believe that phosphates have no effect on algae growth.
    That is not what was said. What was said is that managing phophates is a completely unneccessary part of pool water management.

    Algae does not grow in properly chlorinated pools. If there is no algae, then reducing phosphates (algae food) serves no purpose.
    In my instance, I was having uncontrolled algae problems that could not be controlled by the methods that you are recommending.
    That's incorrect. If you follow the methods we suggest, algae will not only be controlled but eliminated. I suggest you read through the forum about the thousands of pool owners here who manage their pool water without regard to phosphates. Your water and your algae is no different than anyone else's and the correct application of chlorine makes for a crystal clear, algae free pool.

    I might add this is not a topic for consideration and debate. The methods we teach have been working for more than 10 years in thousands of pools. You are free to manage your pool in whatever manner you choose but you will be challenged when you make a case (or offer bad advice) that has been proven incorrect for many, many years.
    Dave S.
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    Re: recurring algae problem

    Quote Originally Posted by Mark92677
    One of the studies (Nitrate and phosphate levels positively affect the growth of algae species found in Perry Pond., STEFFII FRIED, BRENDAN MACKIE, and ERIN NOTHWEHR, Biology Department, Grinnell College, Grinnell, IA 50112, USA) he referred to states,
    "As expected, nitrate and phosphate levels both significantly affected algal growth. These results are supported by Ryan et al. (1972), Frink and Machlis (1968), and Sikka and Pramer (1968) who found that both nitrate and phosphate levels have a significant effect on algae growth."
    Nobody is denying phosphates and nitrates are algae food. Studies like this are to prove that phosphates increase algae growth and have been used to ban phosphates in dishwashing detergent. As freshwater streams, ponds, and lakes do not contain chlorine in the same levels as pools the study is meaningless for pool maintenance.

    100% of pools can be completely cleared of algae with PROPER testing and PROPER SLAMing. The only time it doesn't work to clear algae is when the user fails to either test properly or fails to complete the SLAM properly. While a phosphate remover could potentially help prevent algae, it is not needed when chlorine kills algae 100% of the time.
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    Re: algae and phosphates

    Again thanks to all for the input. Regarding my algae problem, I brushed and vacuumed the pool on the 27th, the day of my original post. I did not SLAM and continued to keep to normal levels of chlorine and brushed / vacuumed once between then and today Sep 3rd. Knock on wood, no signs of algae so far. At this point I'm hoping that my issue is simply a lack of brushing and a "dead" circulation zone. Time will tell.

    As for the phosphate debate. I think everyone agrees that algae thrive in a phosphate rich environment. However, if you eliminate algae with chlorination phosphates become a mute issue. The heart of the issue then boils down to whether high phosphates hinder the disinfecting properties of chlorine. I'm no expert, but I don't think this is the case. Either way, with all due respect, I will explore all other treatments before submitting to the high costs associated with phosphate removal.

  6. #6
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    Re: algae and phosphates

    I think everyone agrees that algae thrive in a phosphate rich environment.
    As will moss and many other plants. That's why use of phosphates is now controlled in items such as dishwashing detergent. But if the Dead Sea were phosphate rich, there'd still be no algae or moss. Dilute the Dead Sea with a heavy influx of fresh water (diluting salt content) and the algae comes to life. Same sort of thing we are talking about here. Properly chlorinated, the phosphates won't matter.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II T100 Sand Filter, CompuPool CPCS48 SWG, TF-100 test kit

  7. #7
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    Re: algae and phosphates

    Quote Originally Posted by parkerman
    As for the phosphate debate. I think everyone agrees that algae thrive in a phosphate rich environment. However, if you eliminate algae with chlorination phosphates become a mute issue. The heart of the issue then boils down to whether high phosphates hinder the disinfecting properties of chlorine. I'm no expert, but I don't think this is the case. Either way, with all due respect, I will explore all other treatments before submitting to the high costs associated with phosphate removal.
    There is no debate except among those who are not well-informed. Algae are limited in their growth rate by sunlight and temperature regardless of the phosphate and nitrate level. So if you can kill the algae faster than it can grow even under these ideal conditions, then you won't get algae. The chlorine/CYA chart is designed to be at a level that prevents green and black algae growth. Yellow/mustard algae is more chlorine-resistant so takes a higher level (roughly double) so instead it's better to completely eradicate it when possible.

    There is no interaction between phosphate and chlorine. There is an indirect issue if the calcium and phosphate levels are both high in that one can get calcium phosphate scaling at the hydrogen gas generation plate in a saltwater chlorine generator.

    Phosphate removers need to be seen in the same vein as algaecides. They are insurance, at extra cost, if you aren't able to maintain proper chlorine levels. They are not necessary. Also, they are not a panacea since they do not remove organic phosphates so if the chlorine gets all the way to zero, bacteria can fairly quickly convert organic phosphates to orthophosphate and algae can then grow much more quickly.
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  8. #8
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    Re: algae and phosphates

    Quote Originally Posted by chem geek
    Quote Originally Posted by parkerman
    As for the phosphate debate. I think everyone agrees that algae thrive in a phosphate rich environment. However, if you eliminate algae with chlorination phosphates become a mute issue. The heart of the issue then boils down to whether high phosphates hinder the disinfecting properties of chlorine. I'm no expert, but I don't think this is the case. Either way, with all due respect, I will explore all other treatments before submitting to the high costs associated with phosphate removal.
    There is no debate except among those who are not well-informed. Algae are limited in their growth rate by sunlight and temperature regardless of the phosphate and nitrate level. So if you can kill the algae faster than it can grow even under these ideal conditions, then you won't get algae. The chlorine/CYA chart is designed to be at a level that prevents green and black algae growth. Yellow/mustard algae is more chlorine-resistant so takes a higher level (roughly double) so instead it's better to completely eradicate it when possible.

    There is no interaction between phosphate and chlorine. There is an indirect issue if the calcium and phosphate levels are both high in that one can get calcium phosphate scaling at the hydrogen gas generation plate in a saltwater chlorine generator.

    Phosphate removers need to be seen in the same vein as algaecides. They are insurance, at extra cost, if you aren't able to maintain proper chlorine levels. They are not necessary. Also, they are not a panacea since they do not remove organic phosphates so if the chlorine gets all the way to zero, bacteria can fairly quickly convert organic phosphates to orthophosphate and algae can then grow much more quickly.
    EXACTLY, I couldn't have stated it better Chem Geek.
    Living in Orange County California near the beach, I have warm weather 90% of the year and it is the mustard algae that has been the constant challenge. Since I have removed the phosphates, changed to a salt water pool, and installed an auto chlorinator which maintains the chlorine to a constant 3 ppm (all other pool chemistry within spec) I have not had to shock my pool or add algaecides for over 2 years which was not the case for the previous 10 years.
    I am getting very positive results for the reasons that Chem Geek so eloquently stated.
    Thank you for your clear description.

    I am just saying, don't discount the use of phosphate removers as they may resolve or mitigate your algae problem depending on where you live and the type of algae you are having issues with. It solved my problem after 10 years of fighting it.
    20K IG SW White Plaster Pool & Jacuzzi -2 HP Hayward EcoStar Pump - 70ft2 150GPM Hayward Pro-Grid D.E. Filter DE6020, Hayward AquaRite SWG Auto-Chlorinator with 25,000 gal Turbo Cell, TF100 Test Kit
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  9. #9
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    Re: algae and phosphates

    Just to summarize for folks who may stumble on to this discussion, phosphate levels do not matter unless you do not maintain proper FC levels for your cya level.
    TFP Moderator who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  10. #10
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    Re: algae and phosphates

    Also, what is being described is yellow/mustard algae that is known to require a higher FC/CYA level to keep away (under high algae nutrient conditions) so we normally recommend completely eradicating it, but if for some reason it's constantly re-introduced then one has two choices -- either maintain a higher FC/CYA level (minimum 15% ratio) or use some form of supplemental algaecide approach. A phosphate remover should be seen as another form of algaecide -- it just operates in a different way. It is quite possible that a weekly dose of Polyquat 60 would also work. As for which approach is more economical, that depends on the initial phosphate level and how rapidly it increases (say, from phosphates in fill water).

    Again, for nearly all pools, phosphate removers and algaecides are not needed if one maintains the appropriate FC/CYA level.
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