Look for algae. Algae growth in your pool will rapidly consume free chlorine. High temperatures, high levels of phosphates, dirty or clogged filters and low chlorine levels can promote algae growth. Scrubbing with a brush can remove algae from surfaces if they have accumulated in one place.
One of the causes of a high chlorine demand is an excessive buildup of algae and phosphates. Although you're adding chlorine to your water, bacteria or algae are overpowering the chemicals causing it not to show up on tests strips or in water kits.
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.
In short, the UV rays produced by the sun have a major effect on chlorine. When exposed to UV rays, chlorine ions begin to separate, which eventually destroys them. And as your chlorine burns away, your sanitizer level drops. This is the very reason why CYA (cyanuric acid), or chlorine stabilizer, exists.
If you test your pool water and can't get a chlorine level reading at all it may be due to a very high chlorine demand. A high chlorine demand is the inability to keep an adequate level of chlorine in the pool water even though the water appears to be balanced and properly maintained.
Why Does Chlorine Lock Happen? The most common cause of chlorine lock is an overabundance of cyanuric acid (CYA). Cyanuric acid is commonly referred to as a "stabilizer" and is vital to maintaining healthy chlorine levels in your pool.
"Shocking” refers to the process of adding chlorine or non-chlorine pool chemicals to the water in order to raise the "free chlorine” level. The goal is to raise this level to a point where contaminants such as algae, chloramines and bacteria are destroyed.
Take out about ¼ of your pool water and then refill your pool water with fresh water. After this, allow the water to circulate for at least 8 hours before checking your chemical levels again. The cyanuric acid levels should have dropped and your chlorine levels should have dropped significantly as well.
If the difference exceeds 0.2 ppm, it means that the combined chlorine in the pool is very high and needs to be reduced. At this point, the best way to reduce combined chlorine and increase free chlorine is to shock the pool water immediately.
Using baking soda will not actually lower your pool's chlorine level. If your ph is way too low it may. Prevent corrosion and damage to pool equipment; To raise your ph levels, it can be as simple as adding seven to nine pounds of baking soda to your pool water.
The fastest way to do this is by shocking your pool. But not the way you normally do. Your best bet is to triple shock it with calcium hypochlorite. To triple shock, add 3 pounds of shock per 10,000 gallons of water.
Chlorine is a sanitizer, and (unless you use Baquacil products) is necessary for maintaining a clear and healthy pool. Shock is chlorine, in a high dose, meant to shock your pool and raise the chlorine level quickly.
The best time of day to shock your pool is in the evening. This is because the sun's rays can affect the effectiveness of the chlorine by dissolving it too quickly, before it has a chance to rid the pool of contaminants and clean the water.
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.
While shocking and adding algaecide is effective in getting rid of algae, 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.
If the pool is still very cloudy or green, you may need to shock it to make it safe to swim in again. First, make sure that the filter system is working properly and the chemicals are still at the proper levels. Next, mix up your chlorine shock (hyperchlorinate) treatment.
Best Time to Shock Your Pool
The best time of day to shock pool is when the sun is down. So, experts recommend shocking your pool in the evening or at night, to make sure it does its job. Shocking during the day can be ineffective as UV rays from direct sunlight significantly reduce free chlorine levels.
Before you start pouring shock in the pool, the first step is to brush the sides and floor of your pool to loosen all the algae. Doing this breaks the skin and allows the pool shock to more easily kill the algae. Once you've done this, it is important to make sure you have the proper pH level in your water.
After Shocking Your Pool
It is safe to swim once your chlorine levels are around 5 ppm or after 24 hours. It is always best to test first!
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.
Shock has a more intense chemical strength than the traditional chlorine sanitizers, and it also differs in how you should apply it to your swimming pool. Short answer: No. Chlorine sanitizers and shock are similar but different in strength.
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.
The best chlorine neutralizer available for swimming pools is still sodium thiosulfate.
Hydrogen peroxide is sold as a pool chemical oxidizer, which means it works to break down chlorine through chemical reactions.
Additionally, vinegar kills bacteria and removes calcium deposits on the pool tiles. The advantage of vinegar over chlorine is that vinegar does not have negative side effects because it does not bleach surfaces and is also natural.