Why and When Do I need to "shock"?

[rtpatter]

This is my second year of pool ownership first year on Chlorine. I basically just been adding bleach so far this year. I have also used a floater with a couple of Tri Chlor pucks as well to supplement. My CYA is at 40 so I'm probably gonna go with just straight bleach for the rest of the summer.

My question is this, so far my water has been perfect I haven't even had to add baking soda or borax the water is crystal clear. I keep my chlorine between 1 and 5. So when do I need to shock? I know from reading this forum that Shock is something you do not buy. However, if I shock my pool with chlorine say taking it up to 15 ppm it would take several days for my chlorine to come back down to normal levels. The shock you can buy at the pool stores supposedly rapidly disapates overnight so that the pool is ready to go the next day correct? So what should I use to shock and should I even bother doing it as long as the water is in balance and everything is clear.

[CarlD]

The shock you can buy at the pool stores supposedly rapidly disapates overnight so that the pool is ready to go the next day correct? So what should I use to shock and should I even bother doing it as long as the water is in balance and everything is clear.

Let your common sense guide you. The pool store stuff is HYPE. Once the "shock" dissolves, it puts chlorine into the water. Chlorine is chlorine is chlorine! There is NO difference in how fast it disapates once it's disolved into the water. Testing your chlorine levels is the best way to learn what to expect.

If your water is fine, shocking isn't necessary. You shock when your water isn't fine to prevent it getting worse.

[Rangeball]

Have you seen this thread?

http://www.poolforum.com/pf2/showthread.php?t=2200

[prh129]

In a nutshell, shocking means to raise the chlorine level high enough to cause a reaction that burns up bad stuff. The chlorine level needed to do this depends on your CYA level. Measuring CC (combined chlorine) is the way to determine of you have enough bad stuff in your pool to shock. Generally 0.5 or under is OK for CC, above that you can shock to bring CC down to 0.

Having a lot of people in the pool can cause CC to go up so it's a good idea to check after you have a lot of people in the pool. An FAS-DPD test is what you need to accurately measure CC. The OTO kit that tests chlorine and pH tests for total chlorine which is CC + FC (free chlorine) so there is no way to tell from the OTO result how much FC vs CC you have.

Peter

[gonefishin]

My question is this, so far my water has been perfect I haven't even had to add baking soda or borax the water is crystal clear. I keep my chlorine between 1 and 5. So when do I need to shock? I know from reading this forum that Shock is something you do not buy. However, if I shock my pool with chlorine say taking it up to 15 ppm it would take several days for my chlorine to come back down to normal levels. The shock you can buy at the pool stores supposedly rapidly disapates overnight so that the pool is ready to go the next day correct? So what should I use to shock and should I even bother doing it as long as the water is in balance and everything is clear.


What type of testing kit do you have?

Could you test for both Free Chlorine and Combined Chlorine?


I'm new at this...but I think that your water and testing levels will be your guide (along with this site :)). If your water and test results indicate a shock is in need...then shock. If it doesn't...then don't bring your chlorine levels up just for the sake of shocking every week or two weeks like the pool stores (many times) suggest. Treat the water...not the pool.


If your FC levels run low...add more chlorine. If your CC levels start to run high...use this as an indication that you need to shock. If you bring your pool up to shock levels when there is no need, then it will take a while to bring the levels down (depending on the weather).

dan