Green Pool With Cloudy Water

by Lisa & Walter Jackson
(Victoria, Texas)

Thanks so much for your website.

We are new to taking care of a 10,000 gallon in-ground pool. We live in south Texas where it is muggy and hot. Our pool is green and the water is cloudy.

Levels are: 8.4 pH, 10 PPM, 120 Alkalinity, 100 Stabilizer

We shocked the pool. Have vacuumed and brushed sides and bottom repeatedly with no change.

With the pump running continuously, early in the evening we put in pH Minus and waited 2 hours. Then we put 128 oz. of liquid chlorine in, brushed the bottom and ran the pump another 3 hours and turned it off over night.

This morning our pH was down to 7.8 but everything else was the same. We have just vacuumed the pool again.

We are clueless as to what do to next.

Please help :)

Thanks for the question and glad you found my site

First thing I noticed with your readings was the stabilizer (cyanuric acid/CYA). It's 100ppm, if I read that correctly. The recommended range for CYA is 30 - 50ppm. What's happening is the chlorine is becoming less and less effective the higher the CYA gets. Stabilizer needs to be 7.5% of the chlorine. This is how to control algae.

This is an easy math equation. Say you run the chlorine at 2.5ppm, simply divide 2.5 by 7.5% and you get 33. Now, as the CYA increases through using tabs, Trichlor tabs, the chlorine needs to increase as well.

If you allow the CYA to get to 100ppm, you need to run the chlorine at 7 - 8ppm for the chlorine to be effective. 7 (chlorine) divided by 7.5% (CYA) = 93. 8 divided by 7.5% = 106. When the CYA gets this high the only way to reduce it is a
partial drain and refill.

There's no chemical to reduce the CYA. Let's use common sense. If your CYA is at 100ppm, and the range is 30 - 50ppm, then by draining 1/2 of the water and refilling it you'll drop the CYA to 50ppm. You really want it to get to 30ppm. As was stated above, the CYA will slowly increase using Trichlor tabs.

You can shock the pool and possibly clear it up, however, it will probably go green again because of the elevated CYA level. Doing this will save alot on swimming pool chemicals in the long run.

The best, and really only solution, is to drain about 2/3 of the water and refill. This will keep about 30ppm CYA in the pool. Next is to run the FILTER for 24 hours then retest all of the chemicals. You need to do this because you're adding so much fresh water. The readings you have right now will not be the same after the new refill.

The pool store might tell you to keep shocking the pool without taking into consideration the high CYA. This is completely wrong. You must get the CYA down so your chlorine can work properly.

Do this and email back with the new readings and we can go from there.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Algae/Green Pool Water" category.

Check back to this post for updates or answers.

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.

If you've found this site helpful please consider making a donation. Thank you.

Hope this helps and have a great Summer.


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May 05, 2013
Green Pool With Cloudy Water
by: Lisa & Walter Jackson

Our CYA is within the "ok" range, according to our test bottle. We are concerned about the cost of 5,000 gallons of fresh water.

I'd encourage you to get your water fully tested from a pool store, even if you have an "OK" reading. If the CYA comes back between 30 - 50ppm you won't need to drain the pool, just balance the chemicals and shock.

I can only go on the readings that are given to me. You got the pH down a bit, which is good and the TA is 120ppm. That's high normal, but still alright. Range is 80 - 100ppm.

Shock is a process. You must manually dose with chlorine and get AND keep the chlorine above 10 - 12ppm. Make the adjustment at night, then retest in the morning, shock again, FILTER 24/7, and backwash once per day.

The pool will go from green to a white/grey cloudy and the chlorine will begin to hold better. You'll lose most of the chlorine, then 2/3, then 1/2, and so on. Once you only lose 1 - 2ppm of chlorine 8 - 10 hours after the last application you know the algae is dead. Now it's filtering and backwashing once per day. Broadcast the chlorine around the perimeter of the pool and brush well. This will loosen up any algae adhering to the walls and bottom.

Jul 16, 2014
Green Pool
by: Charles

My readings are : Free chlorine 19.3, Total chlorine 10.3,comb chlorine 0ppm, pH is 7.7, hardness is 257,alkalinity is 92,CYA is 84, copper is 0.1 per my local pool tests.

I am still green, any suggestions as to clear pool as my wife had back surgery, and we need to exercise.

Oct 14, 2015
Green pool
by: RS

I to live in Victoria. I also have a green pool and my pH has been 7.4, Cyanuric acid 70 to 90, free chlorine 5-10, combined chlorine 0.0, alkalinity 70-80 for three months. I brush, net the pool, run the dolphin on the bottom, and clean the skimmers daily. The pump runs 24/7 and the pressure is 15 mmHg. 2 1/2 months ago I had to drain the pool entirely because of a green sludge that it for responding to know therapy and refill the entire pool. Chemical balance has been maintained since that time with daily cleaning and continuous running of the pool. Hey chlorine feeder uses 3 inch tabs of Trichlor set on maximum feed. In the last week the cyanuric acid increased to about 80-90 in the pool has completely turned green in spite of continued high levels of free chlorine. Other than regular bleach I have had considerable difficulty locating liquid chlorine. The pool was backwashed four days ago. Generally I backwash every two weeks or every week. The sand in the filter was replaced when the pool was drained. Any thoughts? By the way the pool store now claims they have an agent to lower the cyanuric acid. Really??

Hello and thanks for the question. While I've tried to make my site as comprehensive as possible there are some situations that come up that aren't covered. It's impossible to cover every circumstance. Your issue sounds like it falls into that category. The CYA keeps increasing with a green pool and a high FC and we need to find out why. A good place for you to start is the video page: - Green Pool Video Those pictures are from pools that I've personally cleared up, pool owners that have my eBooks, or had personal consults. And you can go to the Q&A page: - Pool Questions and Answers where I've answered over 1000 questions. I also have this page that offers my eBooks and personal consults: - Swimming Pool Resources eBooks.

Again, it sounds as if you have a unique situation so I would be happy to spend the time necessary to address your concerns personally through a consultation. Consultations can be done via telephone or Skype, whichever you feel will meet your need the best. I only charge $37 for this service in an effort to make pool ownership affordable and understandable.

Go to the links above, see if your problem is addressed in a way that's useful to you, and if not I'm available to help.


Jun 11, 2016
Pool Water Is Greenish/Cloudy
by: Breana

My pool water was green I shocked it and now it's cloudy/greenish. I need help making this clear again for my babies birthday! HELP! I have no luck!

Hi Breana. It's helpful to have a full set of chemical numbers including your filter kind, pool size, and everything you've used in the pool so far including algaecides, phosphate removers, etc..

Please remember that I also have eBooks and consults available that detail my F.T.A. Process on clearing up pools:

Clear Blue Pool eBook
How To Clear Up A Green Pool eBook
Personal Phone Consultation


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