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Thread: New filter, bad storm, power outage= algae

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    New filter, bad storm, power outage= algae

    Hello, I have a 25000 gallon in ground pool with a 3/4 horsepower pump. Just got a new filter due to a cracked multivalve. Installed a 24 inch Hayward sand filter. It was doing well until we had a bad storm on Monday (at least 3 inches of rain in 25 minutes) and then a power outage for 30 hours. Pool chemistry levels were ok except chlorine. Shocked pool. Another storm arrived on Wednesday. Luckily power stayed on but another 3 inches of rain in short time. All levels ok. Backwashed and drained the excess water. Now we have algae. Brushed and vacuumed yesterday and shocked again last night, still green. My question is, could it be my new filter. My old one was undersized but would manage ok.

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    duraleigh's Avatar
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    Re: New filter, bad storm, power outage= algae

    Welcome to the forum.

    You did not have adequate chlorine in your pool. The filter has nothing to do with the formation of algae but chlorine (and lack of it) has everything to do with it.

    read "The ABC's of Pool Water Chemistry" up in Pool School. That'll get you started. Everything we teach on this forum begins and ends with your own high quality testing. Do you have one of the suggested kits?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    ship of fools's Avatar
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    Re: New filter, bad storm, power outage= algae

    Quote Originally Posted by Sbruegmann View Post
    Hello, I have a 25000 gallon in ground pool with a 3/4 horsepower pump. Just got a new filter due to a cracked multivalve. Installed a 24 inch Hayward sand filter. It was doing well until we had a bad storm on Monday (at least 3 inches of rain in 25 minutes) and then a power outage for 30 hours. Pool chemistry levels were ok except chlorine. Shocked pool. Another storm arrived on Wednesday. Luckily power stayed on but another 3 inches of rain in short time. All levels ok. Backwashed and drained the excess water. Now we have algae. Brushed and vacuumed yesterday and shocked again last night, still green. My question is, could it be my new filter. My old one was undersized but would manage ok.
    Nope. Post up your "ok" levels and we can help.
    21,000 gallon inground
    Haywood Sand Filter
    Vinyl Liner

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    Re: New filter, bad storm, power outage= algae

    I don't have one of the suggested kits and will get one but this is the first time these conditions have occurred together to allow the algae growth so I haven't needed one before this. I think my biggest issue was I was afraid to put chlorine in the pool without the filter running but I guess that is what you do when you close the pool. I was just concerned that something was up with the filter since it hasn't really been up and running long. I will get a new kit to better check the chlorine levels so this won't happened again and I can better follow the SLAM process. Thanks!

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    Re: New filter, bad storm, power outage= algae

    Quote Originally Posted by Sbruegmann View Post
    Hello, I have a 25000 gallon in ground pool with a 3/4 horsepower pump. Just got a new filter due to a cracked multivalve. Installed a 24 inch Hayward sand filter. It was doing well until we had a bad storm on Monday (at least 3 inches of rain in 25 minutes) and then a power outage for 30 hours. Pool chemistry levels were ok except chlorine. Shocked pool. Another storm arrived on Wednesday. Luckily power stayed on but another 3 inches of rain in short time. All levels ok. Backwashed and drained the excess water. Now we have algae. Brushed and vacuumed yesterday and shocked again last night, still green. My question is, could it be my new filter. My old one was undersized but would manage ok.
    Welcome to the forum.

    As Dave has already stated, your pool turned green from lack of sanitizer (chlorine), not inadequate/lack of filtering.

    Your pump's primary function is to circulate the water. Your filter's primary function is to catch any dirt & debris in that circulated water, and your chlorine's primary function is to keep the circulating, debris free water sanitized and free of algae, bacteria & virus.

    If you had continued to test and add chlorine as needed, and brushed the pool to stir up and mix the water your pool would have remained algae free.

    Concerning the 6 inches of rain, it should really have very little impact on your pool if you are testing & maintaining FC. I can't tell what % of your pool water volume that 6" would be as I don't know the length and width of your pool (please add your pool's details to your signature).

    How do you normally chlorinate? How do you test the water, and how often?

    We can help you clear up that pool with a proper SLAM, but it will require accurate testing.

    Dom
    Dom - TFP Guide
    Intex 18' X 48" Ultra Frame AGP 6700 gallons | Two Intex CS8110 SWG's | Hayward Pro Series 21" Sandfilter | Hayward 1.5HP Power Flo Matrix pump | Hayward Thru-wall Skimmer | Wanda the Whale | 72 sq ft of Sungrabber Solar Panels with Hayward GLC-2P-A | Taylor K2006 Test Kit, Sample Sizer & Speed Stir | Click Here To Become a TFP Supporter!

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