If your water's pH is too high, it hinders the chlorine's ability to efficiently clean the pool. A water pH level that is too low causes the chlorine to dissipate more quickly. Therefore you'll need to add more chlorine to accomplish the task.
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.
Aim to maintain a chlorine level of 3 to 5mg/l at all times. How frequently you add more chlorine will depend on your usage and bathing habits. It could be daily, every two to three days or weekly. For 1mg/l, add 2g per 1000 litres.
How Often Should I Shock My Pool? Shocking your pool regularly will help to keep the water clean and free of contaminants. You should aim to shock your pool about once a week, with the additional shock after heavy use. Some tell-tale signs that your pool needs to be shocked are cloudy, foamy, green, or odourous water.
When you're shocking a pool, the goal is to raise the free chlorine level of the pool water to roughly 10 times the combined chlorine level.
Shocking then releases the combined chlorine and off-gasses the contaminants, increasing the amount of free chlorine in your pool or spa. The question of whether to use a chlorinated or non-chlorinated shock will depend on how much total chlorine you have in your pool or spa.
A pool filter should be run for a minimum of 6 hours after shocking a swimming pool. This is to allow the filter to clean the water and give the shock enough time to fully mix with the pool water. Running the filter after shocking for 24 hours to 7 days is necessary if the pool has a large amount of algae.
Sun Down – You'll want to shock your pool in the evening when the sun has gone down. This gives your pool plenty of time during the night to free the chlorine and clean the water. In the morning, you should be able to enjoy your pool. If you shock your pool during the day, the sun's UV rays will dissolve the chlorine.
Common unscented household bleach (sodium hypochlorite) works well to shock a pool.
Can you put too much shock in a pool? SKIMMER NOTES: It's unlikely but it could happen. It would take a lot of shock to really make the water unsafe for swimming. The best way to make sure you're safe to swim is to test your pool water and make sure free chlorine levels are between 1-4ppm for healthy swimming.
It Should Not Be Done Together
This is because when you mix chlorine and algaecide together, it renders both of them useless. Hence, you should first shock the pool and wait for the chlorine levels to fall below 5 PPM. Only then should you introduce algaecide to get the best results.
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.
During the bathing season, the chlorine is "burned off" by the sun and when you are using the pool a lot, you also need to add up chlorine. As a rule, you must add chlorine every day to keep the right balance during the bathing season.
The ultraviolet rays of the sun can reduce chlorine by up to 90 percent in two hours! And if it's a hot day, warmer water tends to breed more bacteria, and so the pool's chlorine gets used up faster and must be replenished more frequently.
Direct sunlight (UV)
Direct sunlight breaks down chlorine. Without a stabilizer (cyanuric acid) in the water, as much as 90% of free available chlorine could be destroyed within just two or three hours.
Sand filters need chlorine to sanitize the water. The sand is used to remove debris from the swimming pool, while chlorine is added to get rid of bacteria. Chlorine is a sanitizer; Sand is a filter. Your pool needs both of them to function properly.
Adding chlorine besides the shock can increase the chlorine content in the water which can make the entire shocking process useless. Hence, it is better if you don't use the shock and chlorine at the same time. The best time to add chlorine to the pool water is after you have shocked the pool.
Algae will remain in your pool after shock if you've had insufficient chlorine and an overabundance of metal elements in the pool water. Therefore, to start the cleaning process. Remove all the debris from the pool with a leaf net and then let the smaller dirt fragments settle.
Brown pool water is often caused by metals (iron) becoming oxidized in the pool water. If you shocked your pool water and it turned brown you probably have metals. Oxidized iron usually turns a brown or rusty color in the water.
High doses of chlorine, like pool shock, can cause temporary cloudiness as it kills contaminants. High levels of pH, alkalinity, and calcium hardness are more likely to cause cloudy water.
Short answer: yes. Longer answer: it depends on the formulation. The label on every bleach bottle should tell you the ratio of sodium hypochlorite (and available chlorine) in the bottle to everything else. A higher percentage is generally better, as you'll need to use less bleach to treat your pool.
Just like you run vinegar through your coffee pot to get rid of calcium buildup, white vinegar can wipe away this eyesore in your pool. Mix a 50/50 solution of vinegar and water, dip a sponge or soft cloth into it, and scrub that residue away.