A slimy pool cover or concrete floor can make swimming unpleasant, and the slime is often algae and bacterial growth that make the water unhealthy for swimming.
The slimy and often smelly film that floats on the water's surface is a distinct green color, so look carefully for it before going for a swim. If there's an off-smell, don't go for a swim and don't let your dog take a plunge either.
The slimy feel on your pool walls is an early indication of algae growth. To stop algae growth in its tracks, clean the pool filter first. Before adding any chemicals to the pool, make sure you have a clean filter. Cartridge, sand or diatomaceous earth filters all have their own backwashing methods for cleaning.
But is it safe to swim in a pool with algae? Whether mild or severe, it isn't recommended. Significant amounts of swimming pool algae welcome a breeding ground of harmful bacteria that feed on algae. These bacteria pose health risks to swimmers, most commonly resulting in a skin rash.
Chlorine. Chlorine is a slimy-feeling material when it gets wet. If you have chlorine dust or residue on your fingers and then touch the pool water, the pool water will feel slimy. Avoid this by wearing gloves when dealing with all pool chemicals, and never add water to chlorine; only add chlorine to the water.
Proper chemical balance and sanitizer levels will prevent many opportunities for algae to bloom. High pH and low chlorine (or other sanitizer) can give algae a great start.
While the green algae aren't harmful, the bacteria that feed on the algae can cause issues. When you swim in green water, you expose yourself to algae that host bacteria. Swimming in green water could cause bacterial infections on your skin, and you could get sick if you ingest algae-filled pool water.
Shock Your Pool with Chlorine to Kill Algae
This is the main event in clearing a green pool—killing the algae. Pool shock contains a high level of chlorine that will kill the algae and sanitize the pool. For the best results, use a shock that contains at least 70% available chlorine (calcium hypochlorite).
Cloudy Pool Water: Causes, Treatment, and Preventive Measures. Cloudy or milky swimming pool water is caused by seven main issues: improper levels of chlorine, imbalanced pH and alkalinity, very high calcium hardness (CH) levels, faulty or clogged filter, early stages of algae, ammonia, and debris.
The best way to determine if a body of water is safe and the risk of water borne illness is low is to sample the water and check for Escherichia coli (E. coli) bacteria. E. coli is commonly found in the intestines of humans and other mammals.
The Bottom Line about Pools and Chlorine
As mentioned above, you could probably swim in a pool without chlorine without any major health issues. However, long-term use of a pool lacking chlorinated H2O could make you sick or, at the very least, contribute to rashes and other types of skin irritation.
Baking Soda and Green, Blue, or Yellow Algae
You'll need to use an algaecide to kill the algae and superchlorinate your pool to clear the water. After this treatment, test your pH and alkalinity and add baking soda to raise alkalinity to at least 100 ppm and pH to between 7.2 and 7.8.
"Heavy rain dilutes pool chemicals, especially salt and chlorine, which causes the pool to turn green. This means the water is not sanitised or healthy, so it's vital to address this.
Considering how common green pool algae are, we're lucky that they are not directly dangerous.
While mustard algae is not harmful to humans, an overgrowth can attract harmful bacteria like e. coli. What's more, they can cloud the water and stain the swimming pool. Unlike green algae which float on water, mustard algae cling onto the bottom and the walls of the pool.
Use a pool brush to vigorously scrub any pool surfaces covered in algae, including the walls, floors, and steps. Apply a green algaecide according to the directions on the label. Let the water circulate for 24 hours, then brush the pool surfaces again. Vacuum or backwash to remove any remaining dead algae.
Shock is liquid or granular chlorine. You should add one gallon (or one pound) of shock per 10,000 gallons of pool water every week to two weeks. During hot weather or frequent use, you may need to shock more frequently.
Dip your sponge into your soapy water solution and begin scrubbing all the pool's surfaces, making sure not to forget any of the nooks and crannies. Give your inflatable kiddie pool a good rinse to clear any residual soap. Next, grab a clean towel and wipe down the sides to dry your pool.
I think the answer to your question is about 3-6 days. The problem is that the chlorine that you need to keep the bacteria in check is used up more quickly as the temperature rises, the activity increases, and as sweat and other body stuff is put into the pool.
The solution to maintaining a clear pool is to use readily available liquid bleach as your chlorine source. Chlorine bleach, as discussed above, is not bound to a stabilizer, so when you add chlorine bleach to the pool, it will go right to work killing microbes and sanitizing.
It is important to know what exactly bleach is before you put it in your pool. Household bleach, Clorox and liquid chlorine can all be used to sanitize a pool. They are all types of chlorine. Household bleaches such as Clorox usually contain about 5-6% available chlorine, about half that of pool liquid chlorine.