Question about shocking

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setsailsoon

setsailsoon

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TFP Guide
Oct 25, 2015
5,128
Palm City/FL
Pool Size
25000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60 Plus
Folks,

I'm reading with great interest all the stuff in pool school. I have a background in chemistry and I've long known that water chemistry is almost a field of it's own. But I would have never guessed that pool water chemistry is almost a field of its own also. You folks have done a superb job of translating things that are over my head to practical understanding/applications, while staying technically correct. I'm so appreciative of what you do here. So here's my question. As I look through my local pool supply stores I find most pool shock products seem to have the calcium hypochlorite compound. But it seems to me that is adding to potential CH and makes it hard for me to stay true to the TFP philosophy (add only what I really need) unless I really want/need the added calcium. So it seems to me that I should just add to FC using liquid bleach or trichlor (my CYA is pretty low) and stay away from the shock products that really seem to have the wrong shock products. Am I getting this right. I don't see the need to shock right now I'd just like to know if I'm getting this right. By the way, I've also taken to seriously the recommendation that I do a lot of frequent tests to really understand my pool. I bought the TF-100 and here are my results as of yesterday:

DateTACYAFCCCCHPH
31-Oct-15130<202002257.6
1-Nov-15130<201802257.7
2-Nov-15100<201402257.7
3-Nov-1590<201202507.5
4-Nov-1590807.5
5-Nov-1590702507.6


By the way my pool looks fantastic and I let the pool company go last week as well. I've had to go 7 days with no chlorine added to finally get to single digits! PH fluctuations may be partly my color shade errors. I got a great hint from a member here to use a white background and it's really helping.

Thanks in advance for any comments.

Best regards,

Chris
 
We seldom use the word "shock" on the forum anymore. It is chlorine.

There are several types of chlorine available to you and if you read "The ABC's of Pool Water Chemistry" up in Pool School, it will help you sort out which is best for you in a particular situation.
 
Thanks Dave. I've read through those sections... I guess my question illustrates why the term "shock" isn't really a good one to use. If I understand this TFP approach (I'm definitely on the steep part of the learning curve so I may have it wrong) the word shock only refers to the shock level of FC in the CYA/FC chart. But most of the "shock" treatments offered seem to use Calcium Hypochlorite which may or may not be appropriate for shocking depending on the rest of the water analysis... so people that don't have the benefit of Pool School (like me up to a week ago) may be buying the wrong thing. This just flies in the face of what I would have thought prior to reading on this site so I'm checking to be sure I'm getting it right.
 
Yeah, most folks say "shock" as if its a product, or a "one time cure" for what ails their pool. Those folks often don't understand why they can't clear up their water after hundreds of dollars in *products*. Ugh.

We know that algae requires a maintained level of attack to rid the water of all cooties in a concerted effort not unlike taking the whole 10 day prescription of antibiotics even though you felt better after day 2.

Liquid chlorine is the prescription we like! No added CYA or calcium which your pool may not need. And the backbone of our method is the test kit which reads levels higher and more accurately than most freebie tests that are done at the pool store.
 
shock can be a process or a product. traditional pool care has you shock your pool once a week, using shock. Most often that refers to granulated products, many of which contain Cal Hypo like you saw, or others which will raise your stabilizer.

On the TFP program, you do not shock the pool as a routine, and you almost never use a "shock" product. You keep your FC at the appropriate level using liquid chlorine or the occasional pucks in given circumstances.

If you do this properly and diligently, you'll never have to shock your pool. You would only need to shock the pool if you had an algae outbreak, or if your CYA converted to ammonia over the winter, for example. You would raise your FC to shock level, but still just using liquid chlorine to get there.

edit: crosspost!
 
Once again, because of the confusion that pool stores and chemical companies create, we seldom, if ever, use the term shock. We may decide it's best to SLAM your pool and suggst that you use one of several forms of chlorine (depending) but the term shock really has no purpose in what we teach.
You would only need to shock the pool if you had an algae outbreak, or if your CYA converted to ammonia over the winter, for example. You would raise your FC to shock level, but still just using liquid chlorine to get there.
Click to expand...
No, in those cases you would SLAM the pool.
 
Catanzaro said:
Are you wiping the tip of the bottle when testing? Your TA results have increased, unless you added chemicals to increase TA. Thanks
Click to expand...

Catanzaro, It's actually decreasing, spreadsheet has most recent at the bottom... I'm sure there is some operator error/learning going on. I probably got good at wiping after every drop at the first 90 reading. Also these are the very first tests I've done with my TF-100 kit. But at least the FC trend is making sense. I let the pool company go and it has had a week with no chlorine and finally gotten to single digits.

Thanks to all for your comments... I'm learning more and more each day and with each comment/suggestion you all make.

Chris
 
The philosophy at TFP is that if you properly maintain your pool's FC/CYA ratio on a consistent basis, then you should not need to elevate the chlorine levels on a regular schedule -- that is, you should not need to "shock" your pool in the pool industry sense. Part of the reason for the pool industry saying to "shock" a pool, possibly weekly, is that the primary source of chlorine that is promoted is Trichlor tabs/pucks typically used in floating dispensers or in inline chlorinators (or in some cases in the skimmer with "special" Trichlor sticks designed not to dissolve very much when there is no water flow). The buildup of CYA has the active chlorine level drop because the pool industry doesn't say to raise the FC level proportionately. So one "workaround" they have is to "shock" the pool where the elevated chlorine level can temporarily kill off some early algae growth. However, even this band-aid approach stops working if the CYA level keeps climbing with the FC kept constant.

Because the pool industry says to periodically elevate the chlorine level which they call "shocking" the pool, they have designated certain chlorine products as "shock" products, but they are the same chlorine that can be used for regular chlorination. There is nothing special about them. These "shock" products are not always Cal-Hypo. Sometimes they are Dichlor and sometimes they are lithium hypochlorite. Basically, they are any form of chlorine that dissolves relatively quickly so can elevate the chlorine level quickly. Of course, chlorinating liquid or bleach qualifies but the chlor-alkali industry that makes such products doesn't tend to promote them as "shock" and instead promotes them as a regular source of chlorine.

So as Dave says, get the term "shock" out of your head since it's just too confusing. The only time we still use that term is for the specific "non-chlorine shock" product which is potassium monopersulfate (MPS) and even there we should more properly just call it a "non-chlorine oxidizer".

So then the question becomes what chlorine do you use for daily regular chlorination and what chlorine do you use in the rare event where you do need to elevate the chlorine level as with a SLAM if something has gone wrong with the pool water. Generally speaking, chlorinating liquid or bleach have the least side effects since they do not increase CH nor CYA. Technically, lithium hypochlorite would be fine to use, but it is very expensive (about 5x). Now if you have a need for the CH or CYA to be higher then you can certainly use Cal-Hypo or stabilized chlorine (Trichlor or Dichlor) products if you want to. Some pools get sufficient water dilution either during the summer or with short seasons and then dilute over the winter to be able to use these other chlorine sources without continual buildup of CH or CYA.
 
Chem geek,

Thanks for the great explanation of the shock products on the market. Slowly but surely I'm starting to understand. The CYA in my pool is very low and that may be due to the screened cover. Even with the low CYA I only drop FC by 2-3 ppm each day which seems to be normal for higher CYA levels. So I'm guessing the enclosure is almost simulating an indoor pool. Yesterday I finally did drop to 4 ppm FC so I'll run over to Home Depot and get a case of 10%. I've been watching the adds around here and they seem to have the best price right now ($13.48 for 4 gal case!).

Many thanks for what you and the other experts do here!

Chris
 

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Yesterday I finally did drop to 4 ppm FC so I'll run over to Home Depot and get a case of 10%. I've been watching the adds around here and they seem to have the best price right now ($13.48 for 4 gal case!).
Click to expand...

Be sure to check the time stamp (Julian Date) on the bottles. The best price may not necessarily be the best deal. A lot of Forum members use the Generic Wal-Mart or Target brand. I was lucky enough to find 12.5% fresh liquid for the same price as the 8.25% here in NJ.

Here is the "Bleach Prices 2015" thread, which may give you a better idea where the best deal is Florida:

Bleach Prices 2015 - Page 20
 
Catanzaro,

Thanks for the heads up on chlorine sources and date stamp. I did my tests today and chlorine dropped to about 2.5. Finally perfect! Looks like I'll now only be gone a week so I'm going to get it up to about 20 with 1.5 gal of 10% and 1.5 trichlor tablets (~12 oz). Based on the past week. Here's my most recent test results up to today:

Date
TACYAFCCCCHPHActions

5-Nov-15
90702507.6
6-Nov-1547.8Addded 16 oz muriatic acid 31.45%
6-Nov-1580<20402757.4readings 6 hr after acid addition
7-Nov-1580<202.503007.6

Does that look about right?
 
The trichlor tabs will help bring your CYA up, but I'm not sure how well it will support a week starting at FC 20. You loose a % of the chlorine in the water each day, so (ignoring the trichlor tabs for now) it would look some thing like this:

Day 1 - 20
Day 2 - 12
Day 3 - 7
Day 4 - 4
Day 5 - 2.5
Day 6 - 1.75
Day 7 - 1

These numbers are off the top of my head without benefit of a calculator, but I think they are close to your documented loss of about 40% per day.
 
Tim,

Thanks for the help. This part is a little confusing to me. I've got about 9 total days of data starting at 20 ppm FC when I took the pool over from the pool service company. The % drop varies from 10% to 43%. Average is about 23%. Should I use the average of the data in the calculation? I'm thinking maybe somewhere in the middle... say 30%? Here's the data I've got. Please note there are two readings on Nov 6 when I added acid for the first time:
DateTACYAFCCCCHPHActions
31-Oct-15130<202002257.6
1-Nov-15130<201802257.710%
2-Nov-15100<201402257.722%
3-Nov-1590<201202507.514%
4-Nov-1590807.533%
5-Nov-1590702507.613%
6-Nov-1547.8Addded 16 oz muriatic acid 31.45%43%
6-Nov-1580<20402757.4readings 6 hr after acid addition
7-Nov-1580<202.503007.638%


What do you think?
 
Marian,

Thanks, I figured I'd add chlorine with trichlor until my CYA gets close to 30 and then switch to liquid.

Chris
 
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