In general, you should shock your pool when: Algae begins to grow in your pool. The free chlorine level of your pool measures zero. The chloramines or combined chlorine level rises above 0.5 parts per million (ppm).
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.
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.
You should wait one hour per pound of shock product added, and then test the water to confirm the pH and chlorine are in the proper range before letting anyone enter the pool. As a reminder, you want your pH to be between 7.2 and 7.8ppm and your free available chlorine to be 1-4ppm for safe swimming.
Equally important is to balance the water first, before shocking a pool. Minerals, metals and dirt often mix and deposit as stains or scale during shocking, when pool water is not balanced. In addition, chlorine has much more power or efficacy at lower pH levels, so you can use less.
Total Alkalinity (TA) is the first thing you should balance in your pool water. TA refers to the amount of alkaline material in the water. And since alkaline is a pH stabilizer, the number of alkaline substances in water will affect the pH balance.
If your total chlorine level is high, you will use a non-chlorine shock; if it is low, you will use a chlorinated shock. As a rule, you will need to raise free chlorine to 10 times your combined chlorine to hit what is known as “break point.” Therefore, it is good to deal with combined chlorine while it is still small.
Chlorine tabs (placed in a chlorinator, floater, or skimmer basket) maintain a chlorine residual in the water. You do need to use both tabs and shock. Without tabs, the chlorine shock will dissipate quickly out of the water; without shock, the chlorine level will not get high enough to fully sanitize the water.
The main difference between Shock and Chlorine is that the shock is a high dose of chlorine, whose only function is to shock by raising the chlorine level in the swimming pool. On the other hand, Chlorine is a general sanitiser used to maintain a crystal and clear pool for swimming.
Similarities Between Liquid Chlorine & Powdered Shock
Similarly, both forms have a higher concentration of available chlorine than those used in daily chlorination. They also both kill nearly all living microorganisms, bacteria and contaminants with ease.
Unfortunately, you can't shock your pool using your regular 3-inch chlorine tablets. Common chlorine sanitizing products are great for maintaining chlorine levels, but not necessarily eliminating new waste, bacteria and algae.
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.
Brush the pool vigorously, several times after shocking the pool. Do not use a solar blanket until chlorine and pH level are normal. If chlorine level drops to zero within 24 hours, Repeat the shock treatment. Improve filtration with a pool filter cleaner or filter aid like Jack's Filter Fiber.
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.
"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.
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.
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.
Using liquid chlorine raises the pH of the water.
Liquid chlorine does not raise pH. When added to water, liquid chlorine (which has a pH of 13) makes HOCl (hypochlorous acid – the killing form of chlorine) and NaOH (sodium hydroxide), which raises pH.
Wait times for adding pool chemicals
The wait times between adding pool chemicals is usually around 10 minutes each, as that is also sufficient time for the chemicals to mix in the water. Users also under normal conditions can swim roughly 10 minutes after adding chemicals.
Check Total Alkalinity (TA) first, then adjust for proper pH range. Proper TA will buffer pH, that is, it will help to prevent pH fluctuations. Use fresh, high quality test strips. Excessively high bromine or chlorine levels can result in false pH and TA readings.
Rule of thumb is to do the PH first. And do not bother to drive to pool store to spend the extra money for a PH DECREASER. Buy a plain baking soda for 50cents a pound in Walmart! Chlorine will not work fully until your PH is in the proper range.
Adding Shock Directly Into The Pool Water
Don't worry—you can't overshock your pool. But beyond fashion faux pas, adding shock directly to the pool water if you have a vinyl liner can be a disaster. The shock granules will sink the bottom and bleach out your liner.