Green to Clean: How to Clear up a Green and Cloudy Swimming Pool

Updated on July 10, 2018
robhampton profile image

Rob is a licensed pool service industry professional with over 20 years of experience.

Diving into a green pool.
Diving into a green pool. | Source

Help! The Pool Is Green!

Treating a pool that has turned green? This article will get you step-by-step through how to get that nasty pool in shape. I will also cover some basic chemistry and filtering tips to prevent this from happening again.

All information is based on an in-ground home pool of average size, from 12 to 15 thousand gallons.

What Makes the Pool Green?

Algae make it green, and a chemical imbalance lets the algae grow. If there is enough free chlorine in the pool, algae will have a hard time forming. If for some reason the chlorine can’t build up to a high enough level, algae will grow. That's why you shock your pool with chlorine as part of the six-step process below. If the green comes back, you can adjust the levels of other chemicals besides chlorine, as there is more to pool water chemistry than chlorine alone.

Six Steps to Cleaning a Green Pool

  1. Determine whether your water chemistry can be fixed, or whether it's too far gone.
  2. Test the water to determine the pH balance.
  3. Shock the pool.
  4. Pump and filter the pool to regain balance.
  5. Brush and filter the pool again.
  6. Maintain balanced chemistry.

Each of these steps is described in detail below. All information is based on an in-ground home pool of average size, from 12 to 15 thousand gallons.

Step 1: How Green IS Your Pool?

Because if it's too green, these six steps won’t be enough; you may need to have the pool drained and acid-washed, instead of shocked. I have seen many pools that were not just green, but black. In severe cases like this, it is more cost-effective and less time-consuming to simply drain the pool and have it acid-washed, even though it costs money to refill the pool.

This is my general rule for determining whether the pool can be treated chemically or needs to be drained: if you can see at least six to eight inches below the surface of the water, most likely the pool can be treated chemically. An example is in the photo below; you can see the top of the first stair down into the pool.

Once we establish that the pool doesn't need to be drained and can be treated chemically, we can go from there.

An example of green pool water that can be treated chemically.
An example of green pool water that can be treated chemically.

Step 2: Testing the Water

If the pool is green, there’s obviously little or no chlorine in the pool, and if you are going to shock it you will be adding a lot, so testing for chlorine is not very important. But you should test for pH, because if the pH is very high, the shock will turn the pool cloudy. A shocked pool will be cloudy anyway until all the dead algae and other solids are filtered out, but high pH will cause a VERY cloudy pool.

To find out the pH, I prefer to use a high-end test kit, but the cheap test strips will at least give you an idea if your pH is high or low. You want it to be low: 7.2 or lower.

If the pH is high, add one gallon of muriatic acid, which should be enough. Don't worry that you may have added a little too much, because the pool can be a little acid (low pH) for swimming purposes but still at a good pH for shocking. Test the pH again after shocking and four hours of circulation.

Step 3: Shocking the Pool

Once your pH is 7.2 or below, you are going to start by shocking the pool with granular chlorine (calcium hypochlorite). I suggest purchasing a 25-pound container of granular chlorine, rather than the individual one-pound bags they sell at pool stores or large chain stores. You'll save a great deal of money, and you will need chlorine in the future for small doses from time to time. Use five pounds of granular shock, or 10 gallons (four 2.5-gallon jugs) of liquid chlorine. With the filter pump on, broadcast the chlorine evenly over the water, covering the entire pool surface, until all five pounds of shock, or all ten gallons of liquid chlorine, have been used. Be sure to use a good algaecide as well, which you can add after a few hours of circulation. You can also add a floccing agent at this point to cause the dead algae particles to clump together.

I wrote a follow-up article about shocking the pool that answers some of these questions in more detail:

  • How much shock should I use?
  • How long should I run the pump after shocking?

Step 4: Pumping and Filtering

What type of filter do you have? Follow these steps for your type of filter.

  • Diatomaceous Earth (DE) Filter: Before doing anything else, backwash the DE filter. Add fresh DE powder. Then shock the pool as explained above, and run the pump for 24 hours. Make sure the pool drain is not obstructed by leaves or other material while this pumping is going on. If the pool is so green you can't see the drain, just run a brush over the approximate location of the main drain at the deep end of the pool.
  • Sand Filter: Same as for a DE filter, except the backwash time should be a minimum of five minutes.
  • Cartridge Filter: Make sure it's in good condition and rinsed thoroughly. See note in Step 4 below about cartridges.

Step 5: Brushing and Filtration

After 24 hours of chemicals and circulation, you will see an amazing transformation. Your pool should not be green anymore. But it will still be cloudy, and it will need a lot of brushing and filtration for the next few days. There will probably still be a few stubborn isolated green areas that need some brushing.

If your pool is still green after 24 hours, there may be too much of the wrong chemicals, for example an excess of phosphate or cyanuric acid (“stabilizer”).

It will take a while for the cloudiness to go away.

  • For a sand filter, it will take a week or more.
  • Cartridge filters will need to be cleaned more often than other filters during this process: twice a day for at least two days, or until the pool is clear.
  • If you have a DE filter, and the cloudiness does not clear up, your filter may be clogged and need repair or maintenance.

Step 6: Maintaining Your Pool in Balance

Tips for maintaining your pool:

  1. Make sure you have a reliable chlorinating system, whether it is an in-line, floater, or salt system. Chlorine needs to be in the pool always. Throwing a jug of liquid in it once a week isn't a good way of maintaining the pool. A simple tablet chlorine floater is very effective.
  2. Use a water clarification solution.
  3. Clean your filter. DE filters are by far the best filter to have. Although a bit more costly to purchase at first, they will save you both time and lots of money in the long run.

How often to clean your filter:

  • DE filters: Backwash once a month.
  • Sand filters: Backwash once every two weeks. Be sure to backwash your sand filter for a minimum of four minutes; otherwise, you will see filthy water shooting back into the pool.
  • Cartridge filters: Clean it every three to four weeks, unless you see algae in the pool, in which case you should clean more often. Here's more about how to clean a cartridge filter. Soak in trisodium phosphate every three months.

Fun Poll

Do you maintain the pool yourself?

See results

Questions & Answers

  • I shocked the pool, and then waited over 12 hours to go in and vacuum. At this point, the water was a blue cloudy. Towards the end of vacuuming, the pool is now green. I backwashed the filter, and let the pump run for over 12 hours. This morning I went out, it's still green, but clear enough to see to the bottom of the pool. I can see what I believe is algae on the pool floor. But I know if I go in to vacuum, it will be green again. What do I use, what do I do for this?

    So what is happening is that when you vacuum, much of the "green" is shooting back into the pool. You mentioned backwashing, so you either have a sand filter or a de filter. If a sand filter, this makes sense. In either case, the pool needs to be vacuumed to waste so that EVERYTHING is being vacuumed to waste and not returning to the pool. Some systems just have a valve to open to drain the pool, but depending on the plumbing, sometimes when this is open, some flow can continue through the filter and out the pool returns (even though some of it is going to waste). If you can't vacuum all to waste, keep the filter clean (daily) and the pump running for as long as it takes to filter out. But it sounds like you need a floccing agent and a way to be able to vacuum to waste. Check this article on using a flocculant:

    http://hubpages.com/swimming-pools/Cleangreenpool....

  • My pool was so clean all the time, but I changed to another company, and my pool is too green. The company says that somebody used sun creams inside the pool, but they haven't fixed the problem yet. What can I do?

    Suntan oil, lotion, sunscreen, etc., clog the filter. Cartridge filters absorb this the most. Sand filters are not highly affected by this. DE filters will absorb all of the oils, but will just need to be backwashed more frequently. What can you do? Keep the filter clean. Make sure there is plenty of flow. As long as the chemicals are balanced, then make sure the pump and filter are flowing at full capacity. Sunscreen type of products will cause build-up on the filter reducing the flow. Clean or backwash your filter. If it's a cartridge filter, the cartridge may need to be replaced

  • Why did my pool turn green after I missed a day or two of treatment?

    Try checking these things: The filter. Make sure it's clean, and there is plenty of flow. Chemistry: Have the water tested for phosphates and treat as needed. Check the stabilizer and make sure it's under 50. If the chemistry is balanced, I suspect a bad filter and lack of flow.

  • The pool store measured my copper level at .3; they said this is what is making my pool green. My pH was high, and the chlorine was low. I poured a bottle of Metalfree in but after 24 hours, there was still no change. Do you have any suggestions?

    I would question the integrity of the pool store you visited since copper will not turn a pool green. It sounds as though you were the victim of an "upsell". Although it is good to keep your pool free from metals, this is not why the pool is green. Low chlorine and high pH makes more sense. To balance the chemistry (pH, chlorine, and alkalinity), I recommend the pool also be tested for phosphates. Make sure the pool filter is clean and working properly with good flow. (Does the cartridge filter element need replacing? Is the sand filter working properly? Is the DE filter holding the DE powder?) If you have an in-ground pool with a concrete type surface with a serious copper problem, then blue or teal color stains will be visible. A vinyl liner will make it difficult to detect any "metal" type effects.

Comments

    0 of 8192 characters used
    Post Comment

    • robhampton profile imageAUTHOR

      Rob Hampton 

      4 weeks ago from Tampa Bay, Florida

      Hi Margaret. Higher pH will not clear up a Green pool. Although it's good to have balanced chemistry, there is probably something else going on. It's difficult for me to say without seeing everything so I can only make some suggestions. Filtration: make sure the filter is clean and with your water being green, you will need to clean or backwash the filter often...make sure there is plenty of flow and circulation. Have the water tested for phosphates. If present, you'll need to add phosphate remover. Without knowing the setup and type of pump/filter system (which makes a difference for treating a green pool) this is all I can suggest for now. Hope this helped.

    • profile image

      margaret holmes 

      4 weeks ago

      the pool is saying there is to much clorine and not much ph so we put ph plus in and it is still green

    • robhampton profile imageAUTHOR

      Rob Hampton 

      6 weeks ago from Tampa Bay, Florida

      Hi Ron. Since you have a sand filter I'm going to guess it has a multiport valve that allows you to drain to waste? If so, use a floccing agent, drop everything to the bottom and then vacuum out to waste. You'll lose a couple inches of water, but will be worth it.

    • profile image

      RonC 

      6 weeks ago

      I applied recommended chemicals from a local pool store, followed their processes with a powder to start, then 6 pouches of a super shock that were applied over a recommended time period. While this has worked in the past, I have seen absolutely no change in the water this time. I have a 12,000 gallon in ground with a sand filter. Any thoughts?

    • profile image

      Chelsey 

      7 weeks ago

      Thanks for the advice. I went yesterday had had my water tested again but for phosphates. They were through the roof! I treated for them yesterday and this morning I can see the bottom of my pool! Need to carefully vacuum but I might be on my way to a clear pool!

    • robhampton profile imageAUTHOR

      Rob Hampton 

      7 weeks ago from Tampa Bay, Florida

      Chelsey, when vacuuming to waste, you will lose a few inches of water. Sometimes though, in all honesy with above ground pools, it really is best to just start over.

    • profile image

      Chelsey 

      7 weeks ago

      Thanks rob. My ph is 7.2 and I am cleaning my filter 1-3 times a day just to keep it clean and yesterday I added 4 gallons of liquid shock (pool place was closed and couldn’t find the lb packs anywhere else). Today it is much lighter in color and very cloudy. Still can’t see to the floor.

      If I vacuum to waste I will have to order water (we have a well so I can’t fill from home) so I would prefer not to do that but I’m wondering if my only option is to drain it and start over.

    • robhampton profile imageAUTHOR

      Rob Hampton 

      7 weeks ago from Tampa Bay, Florida

      Hi Chelsey. Sorry you're having an issue. As some of my customers tell me "I wish I could just bulldoze this damn pool and fill it with dirt!" lol so I understand the frustration. Make sure you have good filtration. This is nearly as important as chemicals. When it comes to a green pool, I normally add much more than is recommended or as we say in pool industry "nuke it". I would certainly add double the shock they recommended, minus the algeacide. Keep the pH low (7.2 - 7.4) run the pump as often as possible and clean the filter daily until the pool is clear. I have another article about using a floccing agent which may help you only if your system allows you to vacuum to waste. Also did they check for phosphates when testing? Hope I helped some. Thanks for reading.. Rob

    • profile image

      Chelsey 

      7 weeks ago

      I have a 24ft round above ground. Currently the biggest headache in my life. Yesterday I took a water sample to a local pool place and she said my water chemistry looked good but my chlorine was basically nonexistent (which I figured since my pool is green). So I bought the recommended 2 bags of shock with algae crystals in it and added to my pool yesterday. Today almost 24 hours later, no change. Someone please help! I have been fighting my water for over a month.

    • profile image

      R. Lindsey Parsons 

      2 months ago

      The amount of shock packets (5) you recommend is for what size pool? Ours is 25,000 gallons.

    • robhampton profile imageAUTHOR

      Rob Hampton 

      2 months ago from Tampa Bay, Florida

      Eileen Rose.. Thank you for your comment. I, too hope your water stays clean and clear. Sounds like you have it under good control..(DE filter...YES!) always satisfying to hear. Enjoy your pool!

    • profile image

      Eileen Rose 

      2 months ago

      Excellent information. Especially about our DE filter. We have a big 34X18 oval and have had issues. Hope to see clear water the rest of the summer. Thank you

    • robhampton profile imageAUTHOR

      Rob Hampton 

      4 years ago from Tampa Bay, Florida

      Johng743 thank you for your comment, but not quite sure what you mean.

    • profile image

      Johng743 

      4 years ago

      You are my inspiration , I have few web logs and very sporadically run out from to brand. geeceddagkdf

    • profile image

      BarneyBM 

      5 years ago

      I totally agree with robhampton, empty your pool, clean it and fill it with fresh water. I read an article of a person cleaning his son's pool, took him almost a month and liters (a lot!) of bleach, anti algae and who knows what (oh and not to mention the bottles of wine he consumed waiting for the pool to turn from green to blue). I will never swim in that pool, it will kill me!

    • robhampton profile imageAUTHOR

      Rob Hampton 

      5 years ago from Tampa Bay, Florida

      @Traceylee...If you use well water, first you need to be sure the pool water is free of metals. Well water has a high concentration of certain metals. .. Iron, Copper, Magnesium, Chromium, lead, etc.. It can be devastating if you shock a pool with high amounts of metals. There are products you can purchase to rid the pool of metallic content. I've actually turned a pool black (the actual finish turned black) in my younger days by shocking it without testing the metal content. Luckily I was able to fix it with citric acid. Just get a quart or two of metal remover before shocking, circulate for 24 hrs, you'll be fine

    • profile image

      Traceylee 

      5 years ago

      What if you used well water in your pool and shocking or adding chlorine makes it turn green...or brown depending how much shock was used..

    • robhampton profile imageAUTHOR

      Rob Hampton 

      5 years ago from Tampa Bay, Florida

      @Michele..Thanks for inquiring. Sounds like a drain/clean and acid wash to me. If you have anything other than a DE filter, then you will need to drain the pool. The cost of re-filling a pool is not as costly as most people would assume, so don't let that scare you. Less than $100.00 for sure (unless you have some crazy Olympic sized pool) If you have a DE filter, it can be cleaned chemically. let me know if you have any questions at all. I can walk you through both the drain/clean process as well as a chemical clean. Just shoot me an email. Good luck...Rob. . . poolservice@email.com

    • profile image

      Michele 

      5 years ago

      We had some eletrical issues and our pool pump was down for 2 weeks. We live in Florida and between the heat and rain our pool is now black. I put 2 shock treaments in it, but that did nothing. Was going to go get chlorine to put in pool. Should we drain or can we treat to get blue again? Thanks for your help!

    • profile image

      Clayhounds 

      5 years ago

      Nicely written Hub. Also like all the links. By the way, I do have a swamp pool that I will try these steps

    • robhampton profile imageAUTHOR

      Rob Hampton 

      5 years ago from Tampa Bay, Florida

      Dr alex murray.... That is one of the weirdest comments I have ever seen. Sounds like you are counterfeit money maker? Hopefully the feds will give you a call.

    • robhampton profile imageAUTHOR

      Rob Hampton 

      5 years ago from Tampa Bay, Florida

      Cheryl, I hope it helped, thanks for the comment. I'll be sure to check out your site. Rob

    • swimfan profile image

      swimfan 

      5 years ago from United States

      Awesome step-by-step guide. Seems like this is an issue that plagues a lot of pool owners.

    • robhampton profile imageAUTHOR

      Rob Hampton 

      6 years ago from Tampa Bay, Florida

      I suggest highly that you drain and refill. It would cost far less than spending money at those pool stores that try to sell you stuff you don't need. The other alternative is a flocking agent, or "drop out" or "drop and vac" This will sink all of the algae to the bottom of the pool and will need to be vacuumed out to waste. Does your sand filter have a multi-port valve in order to vac to waste? I would consider installing a cartridge filter as well. Will save you a lot of headaches.

    • profile image

      Pixtaker 

      6 years ago

      what do I do about an above ground pool that has the same problem? We've sunk at least $300 at the pool store.....it was clear for 2 weeks, then slowly returned to this pea soup state even while maintaining....we have a sand filter and i can see the top stair almost the second....

    • robhampton profile imageAUTHOR

      Rob Hampton 

      6 years ago from Tampa Bay, Florida

      Johnr54, Thank you for your comment. Battle is a good word for that. I know how difficult cleaning up a pool can be sometimes. Glad to hear you finally have it taken care of. Feel free to post any questions you might have in the future.

    • johnr54 profile image

      Joanie Ruppel 

      6 years ago from Texas

      Very useful hub. I am a widow taking care of a big pool that we use often. I use a pool company to maintain the pool, but am happy to read more about what to do for a green pool. I am happy to say we are crystal clear after 6 weeks of battling the green!

    • profile image

      Richard Stephen 

      8 years ago

      I've had to go through this process a couple of years ago. Your instructions are basically what I did too. The improvement after 24 hours was amazing and the pool looked great after 3 to 4 days. It is important to clean the cartridge filters (if you have them) as the algae will clog them and make your pump work too hard. After a few days of filtering, a clarifier will help clear up the cloudiness. Good hub!

    • profile image

      Karen Reader 

      8 years ago

      From green to clean, I like that! These are some great tips on taking care of your pool. Thanks for sharing.

    • profile image

      Pool Chemicals 

      8 years ago

      Great hub. Breaking this down into steps definitely makes it easier to understand. Thanks for sharing.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, dengarden.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://dengarden.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)