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Thread: What Should I Improve My System to Prevent Algae

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    What Should I Improve My System to Prevent Algae

    I travel. I have a gunite pool, no salt chlorine generator, no chlorinator, can't use copper-based algaecides...given that I can only maintain this pool once every 2 weeks, what do you suggest?



    25,000 gal, Sta-rite Sys III Modular DE filer, 1 hp Sta-Rite motor, a timer, using giant tabs in skimmers, no floor system, 3 returns, 2 skimmers...

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    Re: What Should I Improve My System to Prevent Algae

    First and foremost I would suggest using a mostly opaque to UV pool cover to reduce your chlorine loss from sunlight. What I write below assumes an open pool with 2 ppm FC per day loss, but you can cut down your daily chlorine loss to less than 1 ppm FC per day by using an appropriate cover. The cover can also reduce the rate of pH rise by eliminating carbon dioxide outgassing.

    One approach would be a combination of automated dosing along with supplemental algae prevention as insurance. Automated dosing would include a saltwater chlorine generator or a peristaltic pump or The Liquidator. However, at 2 ppm FC per day, your 25,000 gallon pool would need 5.6 gallons of 12.5% chlorinating liquid over 2 weeks, but The Liquidator does come in an 8-gallon version and with a peristaltic pump you can get a container for whatever size you want. With the pool cover, your usage could be half or less of these amounts.

    As for supplemental algae prevention, Polyquat 60 is usually added weekly for best results but if you don't use Trichlor pucks so don't have the CYA get too high then you could probably have the Polyquat work for 2 weeks. When I first got my pool 11 years ago, I only started to get green algae growth when my CYA hit 150 ppm and I was using Polyquat but only every other week. So with better management of CYA you may be able to get buy with every other week Polyquat dosing (I'd dose somewhat higher than their once a week recommendation).

    Another alternative for supplemental algae prevention would be use of a phosphate remover, but that can become expensive if you have phosphates in your fill water and have evaporation/refill. Also, you need to be careful using it with your DE filter, especially at first, because it forms a lanthanum carbonate precipitate that will restrict flow in your filter if you use too much at once.

    Of course, you could always use a pool service that visits once a week, but they tend to use Trichlor tabs in a floating chlorinator.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: What Should I Improve My System to Prevent Algae

    or SWG

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    Mod Squad tim5055's Avatar
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    Re: What Should I Improve My System to Prevent Algae

    Richard has covered your options fairly well. The think that you should stop doing is the "using giant tabs in skimmers" from your signature. Unless you are running the pump 24/7 this can damage your pool equipment. When the pump shuts down the tabs continue to dissolve, super-chlorinating the skimmer which can damage the plastic parts. When the pump comes on this super-chlorinated water is sucked through the system and it ain't good for the rest of your equipment either. In addition to that, the tabs are adding stabilizer to your water. The more stabilizer you have the higher the level of chlorine you need to have to keep algae at bay.

    chiefwej has indicated his vote for a SWCG and I'll say I love my Stenner pump. I have a 15 gallon chlorine tank and if I fill it I have about a 3 week supply of chlorine for my pool automatically being added.

    As a new person to our little pices of the internet I'll give you our normal advice. To follow the pool care methods taught here you need to arm yourself with the knowledge and tools necessary to care for your pool.

    The tools are not limited to the brushes, vacuum hoses and other stuff you use around the pool, but include the most important item - one of the recommended test kits. You can buy a kit at a pool store, but again the pool store kits generally won't cut it. To effectively practice the TFPC methods, the FAS/DPD chlorine test is essential. All these kits contain that test while very few other kits do.

    The knowledge is condensed in the Pool School link at the top of every page. It is a great community here, but we do ask that you read and try to understand the information being taught.

    Questions are always welcome and folks will try to direct you and teach you the methods.


    So, welcome to TFP!!
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: What Should I Improve My System to Prevent Algae

    I'll go against the consensus on here and suggest a CHELATED copper based algaecide which stays in the water for 3 months. Just keep the TA in range and Ph between 7 and 7.6.

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    Mod Squad jblizzle's Avatar
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    Re: What Should I Improve My System to Prevent Algae

    Quote Originally Posted by markl67 View Post
    I'll go against the consensus on here and suggest a CHELATED copper based algaecide which stays in the water for 3 months. Just keep the TA in range and Ph between 7 and 7.6.
    Why would you want to risk expensive staining and green hair by adding copper? TFP wholeheartedly recommends against it.
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    Re: What Should I Improve My System to Prevent Algae

    Quote Originally Posted by jblizzle View Post
    Why would you want to risk expensive staining and green hair by adding copper? TFP wholeheartedly recommends against it.
    Hence the word chelated and considering his maintenance schedule.

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    Re: What Should I Improve My System to Prevent Algae

    Use opaque cover and a UV lamp in series with the pump. The cover will reduce the amount of light available for algae growth and the UV light will kill bacteria and algae that passes through the system. It is much cheaper than the SWG. It will not kill algae that cling to the pool walls, but you can easily do it when you return home. I have a holiday house in south of France and I am away for months at a time and nobody to take care of the pool. The UV lamp keeps water clear at all times and in few hours we can clean the pool and start using it. I operate the system 12 hours a day in summer time. Later I will decrease the runtime. If you decide to install a SWG, a UV lamp will be a good backup.
    South of France inground rectangular 17k pool - ruber membrane. Sliding dome, black thermal blanket covering 75% of the pool surface. Aqualux 3/4Hp pump, glass media sand filter, Zodillac robot, 110W UV-c lamp, Hayward brominator, Caliente 12kW heat pump.

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    Re: What Should I Improve My System to Prevent Algae

    Quote Originally Posted by markl67 View Post
    Hence the word chelated and considering his maintenance schedule.
    One can still overdose the metal ion concentrated with chelated copper and a rise of 0.3 in pH increases the risk of metal staining (especially in plaster pools) the same as a doubling of the metal ion concentration. We've had lots of reports of problems with all types of copper systems -- copper from copper sulfate, from ionization systems, with silver and/or zinc, chelated copper, etc. Also, if the pool is not going to be maintained for extended periods of time, the risk of pH rise is much higher and that will cause problems even with chelated copper, mostly because the chelation agent breaks down over time from chlorine. Finally, the chelation of the copper has it be less effective against algae so higher levels are needed (usually 0.7 ppm total copper instead of 0.4 ppm) -- in some ways it's similar to the FC/CYA relationship.

    Also, if one really wants insurance against algae if the chlorine level gets too low, then what I mentioned in an earlier post regarding Polyquat 60 (though that requires dosing once a week) or a phosphate remover would help prevent algae growth without the risks of metal staining or turning blond hair green. If this were a vinyl pool then copper would be less risky, but in a plaster pool copper stains are much more difficult to remove compared to iron stains.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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