Too Much Shock

[danwann]

I've read that not enough chlorine when shocking can be bad. Can too much be a problem? I purchased "hth" brand Liquid Chlorinator at Wal Mart - package says 10% sodium hypochlorate. I think my pool is about 12000 gallons.

Package instructions say 58 to 116 ounces per 10,000 gallons. If I used a full gallon would that be too much?

Thank you.


Dan

[Watermom]

How high you need to shock a pool depends on the CYA (stabilizer or cyanuric acid) level. If you don't shock high enough, it won't kill the algae. If you shock too high, you risk fading your liner. (Take a look at the Best Guess Chlorine Chart in my signature below for more about the connection between chlorine and CYA.)

Some brands of chlorine are putting copper in their products. You do NOT want copper in a pool as it is the copper that stains things (including light-colored hair) green! Look at the label to see what all of the ingredients are.

Why are you shocking your pool? Do you have algae? Do you have a drops-based test kit? Can you provide a complete set of current water testing results taken with a drops-based kit? Make sure CYA is reported.

Also, give more details about your pool and tell us what size pump and type of filter you have. Then, someone here can better advise you.

Welcome to the Pool Forum!

[PoolDoc]

I think my pool is about 12000 gallons. . . . . Package instructions say 58 to 116 ounces per 10,000 gallons. If I used a full gallon would that be too much?

One gallon of 10% bleach will add about 8 ppm of free chlorine to your pool. That's not too high to swim in, under any conditions.

But, it may be higher than you need, depending on your CYA level. (High CYA = loss of chlorine activity, but much lower loss of chlorine to sunlight . . . so you need to maintain higher FC levels, but you still use less chlorine than you would with low CYA).

[danwann]

Thank you for the replies. I went ahead and shocked last evening. I thought the water was a bit cloudy, no algae, and I'd read (not here) that shocking should be done once a week. After posting, THEN reading, I see that's not really the case.

I had purchased a drop type test kit but couldn't read free chlorine (nor could my wife) so maybe there's a difference in kits. I am using strips until I find a good kit.

My pool is a pebble tech with DE filtration and a variable Haywood pump. I also have a solar heater.

Another question: If chlorine tabs have stabilizer does the stabilizer always stay in the pool? It seems that the chlorine levels took most all day to go down today.


Thanks again.


Dan

[Watermom]

Typically the stabilizer stays in the pool all season, although sometimes some pools lose it over the winter. The kit you want to buy is the Taylor K-2006 or better deal 2006C. You can order it through the Amazon link in my signature below. Only order if the seller is listed as Amato Industries. Some other sellers substitute the K-2005 instead which you don't want.

[PoolDoc]

I had purchased a drop type test kit but couldn't read free chlorine (nor could my wife) so maybe there's a difference in kits

If you used an OTO (drops turn yellow when chlorine is present) tester, and your pool water sample did NOT turn yellow . . . you have no chlorine in the pool. OTO is not expensive, but it's extremely reliable: no yellow = no chlorine PERIOD. If you want to 'check' your tester, draw a gallon of tap water, add 1/2 teaspoon of bleach, mix, and test: you should see an orange sample result.

By the way, this is what an OTO/phenol red kit looks like:

and, if you click the picture, it will take you to a high quality (Taylor) K1000 kit. Shipping is as much as the kit, but if you can't find one that works locally, order that one.

If you were trying to distinguish "free" chlorine from "combined" chlorine . . . you're not ready to pursue that, yet.

Test strips are VERY un-reliable. Dealer read strips are sometimes more reliable, but stay away from BioLab stores if possible.

Stabilizer is, more or less, permanent UNLESS a biofilm (algae+bacteria community) develops that EATS stabilizer. You do NOT want this to happen, since the bacteria that eat stabilizer, often 'poop' ammonia, and it takes HUGE amounts of chlorine to get rid of the ammonia.

However, right now, we're still at square one: we need a valid OTO chlorine reading, and a valid phenol red pH reading!