If chlorine is kept at proper level, is shocking ever necessary?

[Hubjeep]

Theoretically, should there ever be a need to shock a pool if the chlorine is kept at the proper level?

When my father took care of the pool he would check the auto chlorinater daily (adding tabs). We would go an entire summer with out shocking the pool and it would remain crystal clear.

Now that I maintain the pool (and neglect to add tabs sometimes), it seems as though even if the tester shows up yellow (chlorine) algae can still grow. Did he just add more chlorine than me?

BTW, PH is fine, it almost seemed like the pool was easier to keep clear when it was low though.

Thanks,
John

[Watermom]

Theoretically, if chlorine is kept at the proper level, you never need to shock a pool. However, if you chlorinate exclusively with tabs, which I assume are trichlor, you are continuing to add cya which, over time build up to levels which require higher chlorine to keep algae at bay. I suspect this is what is happening in your pool. Even though your tester shows yellow, your cya level may be so high that you should actually be keeping your chlorine much higher than you are. We actually need a complete set of current water testing numbers to be able to help. Repost with numbers and somebody here can better advise you. We need FC, TC, Ph, alk, cya. Also tell us what type of pool and the volume.

[Hubjeep]

Watermom,
thanks for the reply.

I stopped at Leslie's pool store for a water test. They said everything was fine and sold me a bottle of Ultra Bright. http://www.lesliespool.com/shopping/...ProductID=8174

I added about 20 ounces to the pool, the bottle says to let it filter for a few hours, then vac the pool. It is supposed to bring fine particles together that are too fine for the filter to trap.

The only numbers on the test sheet are:
Free available chlorine= 4 PPM
pH= 7.6
Total alkalinity= 100

It is a 25,000 gallon vinyl in-ground pool.

[aylad]

You need to determine your CYA level, then shock that pool! Keep it at shock level by testing and adding more chlorine 2-3 times daily until the water goes back to cloudy blue. Don't bother with the Ultra Bright--it's a waste of money right now. Just vac'ing the algae out won't completely get rid of it...you have to kill it first. You need chlorine, and lots of it.

Janet

[Hubjeep]

You need to determine your CYA level, then shock that pool! Keep it at shock level by testing and adding more chlorine 2-3 times daily until the water goes back to cloudy blue. Don't bother with the Ultra Bright--it's a waste of money right now. Just vac'ing the algae out won't completely get rid of it...you have to kill it first. You need chlorine, and lots of it.
Janet

By chlorine do you mean shock powder, granular chlorine dumped directly into the pool, or just load the chlorineator with tabs?

Thanks,
John

[Watermom]

Those are all forms of chlorine. We really need to know your cya reading. Those tabs are continually adding more and more cya and when you get too much, it can be a problem. Most of us here on the forum just use plain, unscented laundry bleach as our source of chlorine. What ingredients are in the shock powder and in the granular chlorine? I have a feeling one or both of them may be dichlor powder. It, too, will add more cya. Post as soon as you get that cya reading for us to look at.