Green Swimming Pool Water In Above Ground Pool..Algae..Shock

by BJ
(Clear Up A Green Pool eBook)

I have green swimming pool water in my above ground pool (5600 gal). I am assuming it is pool algae, as we had the same thing last year. I cannot get rid of it and do not have a vacuum either.

Is it necessary?

I have put shock n' swim in, algaecide, clarifier, super shocked it, chlorine tablets, swept the bottom as good as I could to stir up the water to help the filter do its job and flushed the filter out numerous times (full of algae).

What else can I do? The pool chlorine level seems to be almost non existent, which I don't understand as all the shocks I've given it the past 2 days.


Thanks for your question

It does sound like you have an issue with green pool water, but don't worry or panic. You can take care of it, kill the algae, and have a great looking and safe swimming pool.

First of all you need to understand that the pool chlorine is the product that kills pool algae. Pool algaecides are for preventative maintenance only, and even that's debatable. Be sure the chlorine level is kept within the proper range of 1.5ppm - 3.5ppm and the cyanuric acid (CYA) is between 20ppm - 50ppm.

I would recommend getting a Taylor Reagent FAS-DPD K-2006 test kit. It's the best on the market and used by most pool professionals. Your local pool store can order one or you can go online to purchase yours.

Water Testing Kit

Look over these pages:

Remove Swimming Pool Algae

Green Pool Water

Swimming Pool Algaecide

Next, get the pool pH level down to around 7.0ppm. Pool chlorine is more effective at this range.

Swimming Pool pH Levels

For your 5600 gallon pool I would recommend using sodium hypochlorite, liquid chlorine, for your pool shock.

Sodium Hypochlorite

The above links have charts to show how much pool chlorine you'll need to reach the super-chlorination level. You'll need about 2 gallons, but I'd go a little over, maybe 2.5 gallons. It's better to be over than under when shocking a pool. Test the water after the shock to ensure you've reached the chlorine level of 12ppm - 15ppm. Don't be concerned if you go a little over.

Keep filtering 24/7 and backwash once per day. You wrote that you flushed the filter out, which I will assume you backwashed. If the pool filter is full of algae then it's doing its job.

After the shock your swimming pool water might be white or grayish in color. This is normal dead swimming pool algae and will be filtered out. I would highly recommend getting a good swimming pool vacuum.

Swimming Pool Vacuums

This will really help in getting the dead pool algae from the bottom of the pool. If you don't want to clog your pool filter, you can always vacuum to "WASTE". Just keep an eye on the water level. Keep the pool full and don't allow the water level to go below the skimmer. The pool pump might draw in air which will compromise the suction of the pump.

Try to keep the pool chlorine level above 5ppm as this will keep the algae away long enough for the chlorine to do its job. When algae dies it releases phosphates which the living pool algae feed on. By initially keeping the chlorine level above 5ppm you'll kill the other pool algae.

You also need to get your cyanuric (CYA) acid level up. This is done by adding either Dichlor powder or Trichlor swimming pool chlorine tablets. Dichlor to get it in there and Trichlor to keep the level constant.

Swimming Pool Chlorine Tablets

Adjust Your Swimming Pool Chlorine

Once the pool algae is gone and your water is clear, keep this link handy to know what your levels should be:

Swimming Pool Tips

It does take some time to clear up your green pool water. Be patient and your water will come around. I know this sounds a bit much, but it's not. Just remember:

*Get the pH pool level down to 7.0ppm

*Pool shock

*Filter 24/7 and backwash

*Vacuum (eye on the water level)

Best of luck


Comments for Green Swimming Pool Water In Above Ground Pool..Algae..Shock

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Jun 04, 2016
Green Aboveground Oool
by: Kat

My pool cover tore and was ultimately thrown away at the end of last summer, so my pool sat open all winter and is now green and gross.

I have cleaned the majority of the leaves out, added 3 packages of shock, one galon of algicide and have changed the filter twice and kept it running 24/7 for 6 days. It is much lighter, but still green and cloudy. Should we just drain, clean and start over, or continue to shock and filter?

Hi Kat. The absolute fastest and least expensive way to clear a pool is by using my F.T.A. Process. I'd encourage you to watch this video. It's one of, if not THE worst pool on the internet. And it was cleared up using my process.

It's not a "product" you use and cannot be reduced to a couple of sentences. It's a simple process, a method, to clear up pools. It can be found in my eBook:

How To Clear Up A Green Pool eBook

And this is for maintenance:

Clear Blue Pool eBook

I also offer personal 90 minute consults for those who wish to take it a step further to get all of their questions answered.


Jan 10, 2015
The Above Ground Pool...More Like A Pond
by: Lucas S (Canada, Southern Ontario)

I recently moved into a new home. The former owners left their 18' above ground pool. It hasn't been used in a couple of seasons and they never put a winter cover on it.

It's just like a pond. What would be the best way to clean the pool? Should I drain it and clean it and fill it back up with water or just hook everything up and dump a large amount of chlorine in it?

I just wanna know the best way to do it and the quickest way to do it. Thank you in advance.

Thanks for the question Lucas

I will assume that when you say your pool is now a pond, the water level is down, the water is green and thick with algae, and the walls and floor are covered with black and green slime.

If this is the case, and you don't have a huge investment in the pool already, I would suggest you drain and clean it.

You can do a very light acid wash, normally a 4:1 ratio. 4 parts water and 1 acid. You'll probably need to scrub a bit to loosen any slime that's adhering to the floor and walls.

Rinse very well and drain that out the best you can. You can use a power washer, BUT, do this at a far enough range that it won't affect the liner. A wide spray would be best. Or use a garden hose with an adjustable nozzle.

If you simply rinse it off with your thumb on the hose, you're going to have alot of excess water. You can go to this page for all the links to chlorine, pH, alkalinity, and calcium hardness. They will show you what to do and how to do it.

I would suggest getting a Taylor FAS-DPD K-2006 pool test kit. It's the one most pool professionals use and will give you the most accurate readings. Be sure you test your fill water with your kit. This way you'll know what going into your pool and you can make the right adjustments. There's no guessing involved.

You might be able to get pool water delivered to you. This is already balanced out and it should be ready to go. The question didn't mention what kind of filtration you have, but this site has all three kinds of filters, maintenance, and troubleshooting.

Hope this helps and good luck with your pool.


Aug 07, 2012
Above Ground Pool Algae
by: Anonymous

We have an above ground pool-28 foot in diameter with a 8 foot deep end. This year the presence of all the craters created by swimmers has appeared in what appears to be algae pits.

We have had the pool for 5-10 years and this is the first year that all the craters have been highlighted. We have tried algae treatments with no success. They lighten the highlighted areas but then come back dark. There is hundreds of small highlighted areas. They just appeared this year.

What are my options?

Thanks for the question

First, I'd like to have your complete chemical readings:

Chlorine, CYA (cyanuric acid/stabilizer), pH, Alkalinity, Calcium Hardness, and Metals (iron and copper) and names of any algaecides you may have used along with clarifiers, phosphate removers, and/or flocs. It makes troubleshooting much easier and the process of clearing up your pool will go much faster.

You can get this done at your local pool store. Without these numbers I'm just guessing at what the problem is. Get back to me with the chemical numbers and I'm sure I can help.

If you need immediate assistance (within 24 hrs) or for emergency personal assistance, you can make a donation of your choice and I'll answer your questions by phone.

Contact Me



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