YouTube Case Study: How To Properly Shock A Pool

8/16/2012 4:03:52 PM #

Hi Matt, I disagree about using calcium hypochlorite in a vinyl liner as a weekly pool shock. The calcium based product can make the vinyl brittle quicker than sodium dicloro! For a concrete pool, ok but not a vinyl liner!

Lori@B & M Pool Spa & Patio

8/16/2012 4:21:54 PM #

I know there will be some folks who disagree with my methods - it's the nature of this business.

I don't know about the calcium making the liner brittle though. I mean, it has calcium in it, which is good for a vinyl liner and for concrete. Obviously, too much of it can cause scaling which would be bad, but as long as you're checking your chemicals regularly, that shouldn't be a problem.

I like sodium dichlor, but it's more expensive to use weekly. Maybe to dilute the costs you can switch it up every week. That might not be a terrible idea.

Thanks for you comment Lori

Matthew Giovanisci

8/16/2012 4:24:39 PM #

I disagree about shocking a pool once a week, especially with cal-hypo which only adds more calcium...If you need to shock any residential pool more than once a week you have other problems to consider.

S

8/16/2012 4:55:59 PM #

Matt- opinions aside, I think you are doing a great job of providing information to the general public. You help the industry by making this education available.

Jerry

8/17/2012 4:39:14 AM #

Shock as a preventative on a weekly basis for a residential pool is not normally needed. In fact, this can lead to a buildup disinfection byproducts that might not develop except for the excessive chlorine. Commercial pools, depending on the load may or may not benefit.

If you have a heavy bather load, such as from a party, raising the chlorine a bit is not a bad idea and raising it to 30% of the CYA level in the pool will help oxidize the additional bather wastes and disinfect any resistant bio-badies.  Shocking a pool is a process and should only be done when needed with a residential pool.

Granular chlorine  generally adds things to the water.. Dichlor adds CYA and Cal-Hypo adds calcium. They are not always going to dissolve quickly so premixing, as Matt suggested, is encouraged. Failing that can lead to the grains making it to the floor of the pool. That can lead to the bleaching, puckering, or drying out of a vinyl liner or bleaching colored plaster.

Unless the pool is low on CYA, using dichlor will make keeping the correct FC level harder and make the levels needed, both normally and for shocking purposes, higher.

Using Cal-Hypo can lead to excessive calcium hardness in the water. If the saturation index is in the positive, scale will form.

Using lithium hypochlorite is too expensive in the amounts needed for a pool. Its fine for a spa where we have to work with only 600 gallons and thus, use only a small amount.

So if we use sodium hypochlorite for shocking, we only add some salt, it disperses readily and there are no grains to sit on the floor. Its pretty economical and easily obtained. In a pinch, unscented bleach in the supermarket is available too but that half the strength.

Scott Bair

8/17/2012 10:39:28 AM #

Thanks Jerry! I really appreciate it

Matthew Giovanisci

8/18/2012 7:27:38 PM #

Just chiming in to say that Scott hit the nail on the head. The only thing I'd add is that sodium hypochlorite can raise the PH pretty drastically so make sure you keep an eye on it.

Brent Charriere

8/19/2012 6:47:35 PM #

I would not shock a pool in the manner in which you did on the video. You are taking a chance in hurting the liner or plaster. You are not sure to dissolve all the chlorine completely and most people use calcium hypochlorite as a shocking compound, if any did not dissolve itcompletely and some lays on the pool floor it will generate heat on pool floor and dry out the liner and or eat pits in a plaster pool the best way is to turn off the main drains and have skimmers open fully and returns to pool (only return line to pool) open fully than pour the shocking chemical into the skimmer slowly and leave the basket into the skimmer. The chlorine will  than go through the pump in to the filter which is a big trap and breeding ground for algae and bacteria so it will be sanitized and the shock will than be dispensed evenly to pool through the returns. your pool will last longer and the shocking will work better.

Kevin Boylen

8/20/2012 10:23:45 AM #

No wonder people get in trouble, So much misinformation and half truths! Take your water to a pool profesional and get it tested for free and quit wasting money, time and risk hurting yourself or your equipement. If you are going to follow this guys advise make sure the pail is used only for that chemical, the residue from other chemicals can cause the release of deadly chlorine gas! You can also create an exothermic reaction and get blow back all over yourself and what ever is nearby. It's not clear if Buddy is poring the residue in the bottom of the pail in the pool or not. A true shock treatment is done when the combined chlorine level exceeds the total by more than 20%, if you don't add enough you make the problem worse if you add too much your wasting product/$. To the guy who posted liquid chlorine ( 10.;8% Sodium Hypoclorite) only adds a little salt to the pool WRONG you are adding insoluuble sodium hydroxide, which over time damages the liner. I could go on, sufice to say you are dealing with hazardous chemicals read all label directions and follow them closely. The information posted hear is like the old saying "A little information can be dangerous"

Pete Phillips

8/20/2012 4:56:55 PM #

I knew this video would cause a reaction like this. It always does.

Matthew Giovanisci

8/21/2012 12:49:01 PM #

Hey Matt,

You are doing a great job. As I always say when teaching water chemistry classes, it is important to know what type of water you are dealing with when selecting a sanitizer or shock. Source water make up will vary from region to region. Understanding the make up of sanitizers and shock and the by-products they leave behind in the water helps in knowing what is best for a particular region. For example in Seattle there is very little mineral or calcium in the source water so using cal-hypo as a shock or sanitizer here is more beneficial because the by-product is needed. In many cases I would recommend non-chlorine oxidizer or liquid chlorine as overall I believe these accomplish the best oxidation with the least amount of by product interference. You do get salts mainly as a part of total dissolved solids. But that is better than too much CYA which comes from using di-chlor in excess!

Terry Arko

8/21/2012 12:57:24 PM #

so ... wheres the beef...... is there a perfect answer.....  what has the least disolved solids, ... who has the least left overs..... who has the best  H2O......  thankyou for giving all who read these ideas..... definitly no control freeks here..... just good stuff..... keep it up.....

patrick

8/21/2012 2:01:20 PM #

I agree, Matt...you are definitely providing a service to this industry with the resources and education you provide on your site. It's good to see the back and forth here - it means folks are passionate about what they do...and, that there is 'no one size fits all' oftentimes.

Keep up the good work!

Shelly

Shelly

8/21/2012 2:04:34 PM #

Matt - Thanks for your effort to educate pool owners and operators.  

Shock treatment is an old term that means different things to different people.  The one factor all definitions have in common is they all involve adding a large dose of an oxidizing chemical to reduce contaminants.  For simplicity, pool and hot tub contaminants can be separated into two groups - living and nonliving.  This is important because it dictates what oxidizer can and should be used.  If the purpose of the "shock" treatment is to kill something, like algae, a chlorine-containing oxidizer is required and appropriate.  If the purpose is to reduce organic contaminants introduced by bathers (bather load), either a chlorine or a non-chlorine oxidizer can be used.  It is however important to note that there are unintended consequences to using a chlorine oxidizer to remove organic contaminants, namely they form combined chlorine.  Adding large doses of chlorine to pool water actually increases the formation of combined chlorine and related disinfection by-products (DBPs), like chloramine, trihalomethane, and many others.  

The most effective way to reduce organic contaminants and lower combined chlorine is to incorporate a non-chlorine oxidizer into the treatment program, and add it on a regular basis.  Regular oxidation reduces contaminants on a regular frequency so they never have a chance to build up and cause problems.  So, how often is regular?  The answer depends on how much the pool gets used.  The more a pool is used, the more frequently it requires oxidation.  If a pool is used daily, it will benefit from weekly oxidation.  If it is used less often, oxidize less often.  The key point is that oxidation, combined with filtration, removes contaminants, so the dose and frequency of oxidation should be based on the introduction of contaminants.  A good rule of thumb is to add one pound of oxidizer per 10,000 gallons of water per week, and then fine tune the frequency based on bather load.  

There are three basic components of pool and hot tub chemistry.  They are (1) sanitation, (2) oxidation, and (3) water balance.  Sure there are times we'll need other supplements, but these are the basics.  Why ignore oxidation?  Why ignore non-chlorine oxidation?  Why wait until problems arise?  Oxidize on some regular frequency (based on bather load) to prevent problems before they start.  Shocking only when needed to correct problems adds cost and makes work, a combination that makes for unhappy pool owners.  

Ed Lightcap

8/21/2012 2:48:10 PM #

  Like others have said there is alot of information and misinformation out there. I would encourage everyone in this industry to keep researching and learning. Just because "that's the way we always do it" or "thats what Joe told me 20 years ago" does not mean we do not need to try new things or change the info we once thought was "gospel"

  Pete Phillips  although you seem fairly knowledgable, it may serve you well to check your facts before you go lecturing others i.e. A true shock treatment is done when the combined chlorine level exceeds the total by more than 20%     I assume you mean when the total or combined exceeds the free chlorine. Also why wait for it to reach 20% considering combineds can be noticed and irritating at 0.2-0.5% ppm?

Dan Reid

8/21/2012 3:34:29 PM #

Thanks for all the support guys. This is great!

Matthew Giovanisci

8/23/2012 11:08:34 PM #

I've been checking this Matthew Giovanisci guy for a little while. I'm not sure where he recieved his education about swimming pools, but he sounds just like the inexperienced pool retail store employees plaguing Florida. I'm seriously worried about the fact that many people seem to see him as a reliable source of knowledge. This is just not the case. There is so much misinformation in the pool industry, and people taking it and spreading it without ever questioning it is a major problem. Matthew has repeatedly used incorrect terms, failed to bring up important points, and hasn't shown me anything that would indicate he is a good candidate for being a trusted source of pool technical information. I can't be the first pool professional to have this thought.

Justin Rashaw

8/24/2012 9:33:39 AM #

Service professionals have different ways of doing things, and at times use different terms to describe the same things. Rather than attacking Matt's credibility, why not offer examples of these incorrect terms or omissions?

barrett kilmer

8/26/2012 10:02:45 PM #

Hi, folks. We have been in the swimming pool business for 41 years near Houston, Texas, and I find nothing wrong with Matt's advice on shocking the pool. One thing the comments here are not taking into account is perhaps the most important variable of all- climate and water temperature, as well as bather load and location.

When your pool is in an area with frequent 100 degree- days- plus of direct sunlight, punctuated by occasional bouts of gully-washer rains and in between the Little League team of 15 eight-year old boys swims in your pool and drinks 10 gallons of koolaid without going into the house to the bathroom, um, yeah, your pool may very well need shocking once a week, or more.  If you have lots of trees and organic material blowing into the pool, as well, yes, it will prevent problems to  do a regular shock.

Like most issues with water chemistry, it depends on your individual conditions.  As for products, all the ones mentioned can be used to shock  with cal hypo properly diluted as Matt advised working just fine in  pools and being less expensive than some of the other products. Liquid chlorine is ok too, but has a very high pH and you need  to be aware to lower it with acid to the proper level if needed.

I cover shocking in some detail in my pool care book, and also recommend at least monthly professional water testing at a good pool store ( like yours) in addition to home testing. And as I mentioned, look at your individual conditions and adjust your recommendations accordlingly.

I do know after 41 years' experience taking care of pools in Houston, it is a good idea to shock regularly depending upon the season. We have almost summer, hotter than homemade sin summer, just was summer and chilly seasons here. In addition to oxidizing organic contaminants and killing bacteria,  shocking also breaks apart combined chlorine ( chloramines- a chemical tie-up of chlorine and ammonia) and reactivates your combined chlorine into "free" available chlorine, so it can effectively do its job again.

Merry

9/7/2012 9:16:57 PM #

If all of you would just add an Ozone generator to your systems shocking would be reduced to almost nothing.  No by products, no added TDS, no chloramines etc.  AND it doesn't have to be expensive.  
A simple Del Ozone EC 1 will handle spas and small pools. An EC2 an average residential. and an EC4 will handle the large little league bombarded punch bowl. And it does it for pennies.  For summer seasonal pools the use is for three to four months a year.  I use these on commercial spas and pools 24 - 7 and get three to four years of use.
And no I am not a sales rep or affiliated with any manufacturer, just a veteran of 31 years in the industry.
Corona discharge is the best in my opinion.
The next greatest intro into our industry is Pentairs ORP,pH, Ozone system. It will enable you to use any sanitizer from salt to liquid and tabs. You will just need to use your head a bit and fabricate the feeder of choice to the system.
Yeah, automation, your car has cruise control, why not your pool?

Zee

Stan Zielinski