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Thread: Recurring Algae Problems

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    Question Recurring Algae Problems

    I thought I had my pool stabilized and then I started working on my pump times. I have a single action pump. I started with 4 hours and it seemed okay, then went down to 3 1/2 hours and it was okay, then went to 3 hours and started having algae issues/cloudy water. After I had decreased the pump time to 3 hours, I used the solar heater and thought there may have been something lurking in there that caused the issue. So once again I tried 3 1/2 hours for a week and it was okay, then went down to 3 hours and got algae again. So once again I slammed the pool and went back to 3 1/2 hours. I had been using the FC range for CYA of 50. There were no issues for some time, but there were 2 different days (not in a row) recently that I forgot to test the pool. The following days the chlorine was about the low end of my range (CYA = 50), so FC = 4, and one day it was around 4, then the other day after I missed testing it was too low (FC = 2). Both days I added chlorine for my target of 6. Would that one day of it going low cause algae? Or is the pump run time the issue (perhaps I should bump it up to 4 hours again)? If not, what do you suggest? I was reading about borates and wonder if maybe that will solve this issue. Any advice is welcome. Thanks so much!
    11,400 Gallons, IG Vinyl, Pentair 188592 Quad D.E. Cartridge Style D.E. Pool Filter 60 Square Foot 120 GPM, Pentair 011018 IntelliFlo Variable Speed High Performance Pool Pump 3 Horsepower 230 Volt, 1 Phase Energy Star Certified, replaced liner 8/2011, TF-100 Test Kit.
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    Mod Squad tim5055's Avatar
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    Re: Recurring Algae Problems

    Pump/filter issues should not cause algae problems. Chemistry does. Too high CYA or too low FC does.

    Are you sure you have complete the SLAM's?
    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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    pwrstrk's Avatar
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    Recurring Algae Problems

    Your FC fell 2ppm below the min of 4. That's the cause. What are your CC's ? Pump runtime is not the cause of algae. FC falling below the min for your CYA level is. Keep your FC in range at all times and you'll be algae free. You can have a properly chlorinated pool and not run your pump for days and won't get algae. Pool may be dirty but it will be algae free.
    I would RE-SLAM the pool until all three criteria are met.
    Crystal clear water.
    CC of 0.5 or less.
    Pass the OCLT.
    After the SLAM your FC range should be a target of 8 and never below 4. 😎
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

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    Re: Recurring Algae Problems

    In case it wasn't brought up before when you did your SLAM you should also check to make sure you don't have any algae in your light niches or clinging to the underside of your ladders or anything else hanging into the pool. Between having a little green patch hiding away that the SLAM doesn't completely kill and then going a little low on FC you can get green pretty easy.
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    Re: Recurring Algae Problems

    If you don't circulate the water long enough, then areas with the worst circulation and long periods of time with no circulation can have the chlorine used up locally and algae can then grow. Lower run times are OK when the water temps are lower because algae growth is slowed. Pointing returns in a direction that improves circulation can help.
    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
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    Re: Recurring Algae Problems

    At higher the water temperatures you need longer pumping time. The algae doubling time is dependent of temperature. At lower temperatures you need to run the pump less, at higher temperature is opposite. At higher temperatures chlorine will outgas faster as well, so you may need to add chlorine more often. It is logic to run the circulation system longer if you have a heater.
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    Re: Recurring Algae Problems

    Just to second and third...Algae only grows in a pool when FC is lacking. As chemgeek says, this will be worse where there are areas of poor circulation. First thing is to increase and maintain proper FC. You can bump up the run time, and shave it down later, but the FC must come up and stay up to suggested levels.
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    Re: Recurring Algae Problems

    Thank you everyone! Each time I slammed the pool, i met all three tests (overnight test, clear water, cc test). My CC has always been 0 to .5. From your feedback, the algae must have started from a patch we did not remove, or a poor circulation area the first couple of times, and this time due to the FC getting too low even if only for a day or two. I will move up my target FC to 8 after reading your feedback, and be more diligent in my testing. Those 2 days recently I did not test I was very busy and forgot till the next day but after this, I think I learned not to let that happen again! Hopefully these steps will help.
    11,400 Gallons, IG Vinyl, Pentair 188592 Quad D.E. Cartridge Style D.E. Pool Filter 60 Square Foot 120 GPM, Pentair 011018 IntelliFlo Variable Speed High Performance Pool Pump 3 Horsepower 230 Volt, 1 Phase Energy Star Certified, replaced liner 8/2011, TF-100 Test Kit.
    ~Kellie

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    Re: Recurring Algae Problems

    Thanks for taking the advice everybody gave ya. You see where the mistake was made and going forward you'll know better. It's only pool water in the end !
    Keep us posted in how things go and if you have any other questions ask away. 😎
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

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    Re: Recurring Algae Problems

    Algae double in population every 3 to 8 hours so it does take a couple of days for enough growth to notice it. At 3 hours per doubling, that's a factor of 256 over 24 hours but 65,536 over 2 days. In practice, algae are limited in their growth rate from algae nutrient, sunlight, and temperature so usually grow more slowly than this worst-case scenario. Nevertheless, you shouldn't let the FC/CYA ratio get too low for too long.
    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
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    Re: Recurring Algae Problems

    I suspect energy costs in Cali may be higher than in my neck of the woods, and I know lots of people on TFP seem to prefer reducing pump times as a result, and experiment a great deal with run times.

    But wouldn't it make sense to also increase the pump run time to keep the (properly) chlorinated water moving? Especially after a slam? For the poster in question, I just want to say that while indeed you need to be above min ch level at all times, in your shoes I'd note com geeks' comment about the importance of circulation in addition to the advice about chlorine.

    By way of background, I know pool stores are typically a bad source of advice, but once I TFP'd my foreclosure pool into submission, I had a conversation with the owner of an indie pool store/service who proved to be a rare unicorn in the industry (Meaning she "approved" and lauded my new-found TFP approach.) Something she said stuck with me...we were discussing solar covers, leaf debris and run times and she said her philosophy was that the most perfect water, eg her own pool, received open air (no cover because she liked to look at it) and lotsa movement (she filters 24/7) and that next to proper sanitation, running the filter was the cheapest preventative medicine for most pools. (Note...the "cheapest" part may not be true in CA, of course)

    I've experimented a bit since, but to keep the pool heated and leaf/pollen/floral/ etc. debris moving I've settled on constant filtering because I don't notice much difference in expense (eg maybe $30-40 a month in energy) and I just like how clean things stay. So I'm biased. But curious apart from expense if there is an upside to reducing run time.
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    pwrstrk's Avatar
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    Recurring Algae Problems

    I run my pump 4-6 hrs a day and water is perfect for me. Nice and clear, sparkly. Running a pump and filter 24/7 is overkill IMO.
    I've also gone for two days with no electric, lent the generator to somebody who needed it more than I did and with just adding bleach and brushing twice a day it stayed algae free. 😎
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

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    Re: Recurring Algae Problems

    My pool is covered most of the time except for about an hour or so every day when my wife uses it for swim therapy or longer on weekends when I may also use the pool. We run the pump 8 hours per day but that's mostly to maximize time for the solar heating. The pool sweep is also on for 2 hours per day. The pool stays very clear as shown during the day and at night. During past winters when the pool was not used and the water got colder, I cut the run time to 4 hours but all at low speed (26 GPM) and I could probably have gone lower without any issues.

    The amount of circulation needed in a pool depends on the bather load and on what gets dropped into it and needs to be filtered out. More filtering will not prevent algae growth. Chlorine does that. One certainly needs circulation to move the chlorine around, but that doesn't need 24/7. Usually one turnover per day is more than enough for most residential pools, but it really does depend on these load factors and the real way to know is to lower the pump run time until you start to notice a change in water clarity and then raise it above that threshold -- that is, set it to the level that is satisfactory for your pool.
    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
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    Re: Recurring Algae Problems

    That makes sense.
    In my case, its likely a moot point to do anything more than periodic shut downs for a few hours at a time as opposed to leaving it off overnight, which I previously tried....I swim every morning and do not have a good footprint for a cover. So I'm kinda stuck leaving everything running to keep the heat up and the myriad debris skimming out Our pool sits in a terraced bowl surrounded by all sorts of flora and a forest upwind, so it truly take the skimmer, pool skim, and the robot each morning to manage the various debris that blows in
    In ground extended Grecian, 22,000 gal, Hayward 220t sand filter, vinyl liner, dolphin m4 supreme.
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