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.
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.
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.
Although, if you overdo the shock treatment, you risk getting green hair from chlorine due to the excess chlorine oxidizing the copper in the water. You can execute a shock treatment with a few different types of pool shock, just be mindful of how much you're using.
It is recommended that chlorine be added at the end of the day once the sun has set and there are no more bathers in the pool.
When diluting, always add the chemical to the dilution water to prevent splash out of the chemical. Liquid chlorine is not stabilized and will burn off quickly in sunlight. Therefore, it should be administered in the evening, after the sun has set.
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.
However, after shocking the pool, you shouldn't vacuum for at least 24 hours. Running the water pump during this period will allow the shock to do its job.
This is why many pool experts recommend that you turn down, or shut off, your saltwater chlorine generator (SWG) while you're shocking your pool. Otherwise, you're running the risk of damaging the salt cell. And that could lead to it not generating enough chlorine after the shocking process finishes.
Best time is either after sunset, or when you need it. Bleach doesn't lose concentration overnight unless it has something to work on. In fact, a good way to tell if your pool is in good shape is to do an overnight chlorine test. Ideally, the FC at night should be the same as the FC level the next morning.
Depending on how much you have added and the size of your pool, it is generally safe to wait about 4 hours after adding liquid chlorine or until levels reach 5 ppm or lower.
Liquid chlorine and granular shock have the same active chemical that sanitizes your pool, what changes is the strength and the way you use it. Liquid chlorine is less costly, unstabilized and comes in liquid form. Granular shock is stabilized and comes in a solid form that dissolves in your pool.
Keep your pump and filter running. Give the shock a good 12 to 24 hours to work it's magic. If the algae hasn't cleared up after 24-48 hours, clean and brush the pool and add another shock treatment.
Pools can immediately turn green after shocking when they have metals like copper in the water. These metals oxidise when exposed to high levels of chlorine which makes the pool water turn green. Adding a metal control product such as Zodiac Metal Remover will help to restore the pool water.
SKIMMER NOTES: No. Chlorine and shock are not the same thing.
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 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.
So if you buy liquid shock, be aware that it only lasts one to two months at the most before it starts to lose effectiveness. While many swimming pool chemicals stay good for years if stored correctly, some pool-maintenance supplies expire more quickly.
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.
Before getting in
Don't swim or let others swim if sick with diarrhea. Shower for at least 1 minute before you get into the water to remove dirt or anything else on your body.
Liquid Chlorine: Depending on how much you have added and the size of your pool, it is generally safe to wait about 4 hours after adding liquid chlorine or until levels reach 5 ppm or lower. After Shocking Your Pool: It is safe to swim once your chlorine levels reach 5 ppm or lower, preferably at 3 ppm.
In theory, if you have a cloudy swimming pool, you can add chlorine to “shock it” and clear things up. Chlorine will get the job done. But, the amounts may vary and you may have to really pound the pool with chlorine to get the water totally clear.
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.
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.