How to Clean a Green Pool
Green Pool Water?
If opening your pool this spring had you scratching head, asking how to clean a green pool, chances are, you have an algae problem. Join the club. The picture to the left is how my swimming pool looked on Sunday May 23rd 2010 when the cover was removed after a long, cold, wet winter in Colorado. The photo to the right was taken just 7 days later on May 30th, 2010. Last year my pool water was much clearer, despite the fact that I used the very same method to winterize and close for the season. The wetter, colder weather throughout the winter and spring obviously played a role in making my swimming pool look more like a pond. There is only one thing that will clear up a cloudy, green, slimy swimming pool: chlorine, and lots of it! The good news, as you can see by the photograph, is that you can make your pool water sparkling clean in just a few days. The key is to get your pool water up to the proper shock level and maintain a high level of chlorine for a few days. So how much is enough? This is where you will want to do some quick tests.
For a non-salt water (SWG) swimming pool like mine, I like to keep my normal, swimming chlorine level around 4-7PPM. For regular shocking, I usually go up to about 15PPM, and after a long winter, around 25PPM. In order to determine your own chlorine levels, it is necessary to know your CYA (Stabilizer). Many people are not aware of the relationship between CYA and Free Chlorine. The higher your CYA, the greater amount of free chlorine that is needed to properly disinfect your pool. A good rule of thumb is to maintain a free chlorine level that is 8% - 12% of your CYA level. My own CYA was around 50PPM when I closed the pool last winter, so I like to keep the FC (Free Chlorine) around 5ppm, which is 10%. For high shock level, I bring my FC up to 50% of the CYA, or 25ppm. For a regular shock level (once a month or so), I would take the FC up to about 15ppm or 33% the level of the CYA. As you might have guessed, high CYA levels make it more costly to keep your pool properly chlorinated. A good goal for a non-SWG swimming pool is a CYA level of around 30-40PPM. Commonly used trichlor pucks contain stabilizer, which is why I only use liquid bleach or cal-hypo to chlorinate my pool.
As you can see from the photo, my pool looked pretty bad. Bad enough, that I skipped the tests and went straight to the liquid Bleach. Based on my 40-50 CYA, my goal was to get the shock level up up to about 25ppm. I used 3ea, 182oz jugs of 6% liquid bleach. To calculate your own needs, use either the Pool Calculator website or if you have an iPhone, I highly recommend Jason T. Linhart's, Pool Calc Application.
Three days after bringing the shock level up to 25ppm, my chlorine was still holding at around 18ppm and the water looked nearly crystal clear, though not quite as good as the 7-day photo above. Probably the most impressive thing about the transformation, is that very little if any brushing of the pool steps and sides were required. The shocking with the liquid bleach and a couple of vacuum jobs are all that was required to make the pool sparkling clean and ready for swimming.
Contrary to popular belief, it is safe to swim in a pool with chlorine levels of 10ppm, as long as your CYA level is not dangerously low (0-15). In fact, the dangers of swimming in a pool where the chlorine isn't high enough far outweigh any risks of swimming in a properly disinfected, high chlorine pool.
For a non-salt water (SWG) swimming pool like mine, I like to keep my normal, swimming chlorine level around 4-7PPM. For regular shocking, I usually go up to about 15PPM, and after a long winter, around 25PPM. In order to determine your own chlorine levels, it is necessary to know your CYA (Stabilizer). Many people are not aware of the relationship between CYA and Free Chlorine. The higher your CYA, the greater amount of free chlorine that is needed to properly disinfect your pool. A good rule of thumb is to maintain a free chlorine level that is 8% - 12% of your CYA level. My own CYA was around 50PPM when I closed the pool last winter, so I like to keep the FC (Free Chlorine) around 5ppm, which is 10%. For high shock level, I bring my FC up to 50% of the CYA, or 25ppm. For a regular shock level (once a month or so), I would take the FC up to about 15ppm or 33% the level of the CYA. As you might have guessed, high CYA levels make it more costly to keep your pool properly chlorinated. A good goal for a non-SWG swimming pool is a CYA level of around 30-40PPM. Commonly used trichlor pucks contain stabilizer, which is why I only use liquid bleach or cal-hypo to chlorinate my pool.
As you can see from the photo, my pool looked pretty bad. Bad enough, that I skipped the tests and went straight to the liquid Bleach. Based on my 40-50 CYA, my goal was to get the shock level up up to about 25ppm. I used 3ea, 182oz jugs of 6% liquid bleach. To calculate your own needs, use either the Pool Calculator website or if you have an iPhone, I highly recommend Jason T. Linhart's, Pool Calc Application.
Three days after bringing the shock level up to 25ppm, my chlorine was still holding at around 18ppm and the water looked nearly crystal clear, though not quite as good as the 7-day photo above. Probably the most impressive thing about the transformation, is that very little if any brushing of the pool steps and sides were required. The shocking with the liquid bleach and a couple of vacuum jobs are all that was required to make the pool sparkling clean and ready for swimming.
Contrary to popular belief, it is safe to swim in a pool with chlorine levels of 10ppm, as long as your CYA level is not dangerously low (0-15). In fact, the dangers of swimming in a pool where the chlorine isn't high enough far outweigh any risks of swimming in a properly disinfected, high chlorine pool.
Now, you know how to clean a Green Pool.