liquid chlorine vs Leslie's tablets?

LeeM2

Well-known member
Jul 3, 2010
96
I purchased the TF100 10 days ago and fully tested my water 3-4 times since, testing chlorine and ph daily. All the parameters stay the same, even after rain which added ~~3-4 inches, except maybe chlorine level went down by 1ppm. I have not shocked for 2 weeks now (used calcium based shock weekly before) and haven't added any bleach to my water.

I have 3-4 tablets in the floater and they seem to keep my chlorine level without upsetting other parameters.

I know the pool school mentions that tablets would cause CYA levels to rise and is not a good choice for cartridge filters (I don't understand why cartridge filters. Can someone explain?). Should I still switch to bleach or Leslies tablets somehow better then other ones out there and can be used instead of bleach?
One of the reasons I'd like to use tablets - I have about 25lb of them and they smell so bad so I want to get rid of them this summer. I keep them in my garage, not sure if I can keep them outside at 95 F. I also purchased 6% "ultra" bleach at Aldi's and 12.5% liquid chlorine, which I need to use before the end of the season, but that should go fast if I stop using tablets or if I shock my pool a couple of times.

Also, 2nd question - I know people here are against shocking pool for no reason. So, is it safe to say that if I keep my chlorine level where it should be (according to CYA\FC chart) I don't need to shock EVER (except when opening the pool I guess)?

Thanks
 

LeeM2

Well-known member
Jul 3, 2010
96
salp said:
What are your numbers? What is your CYA?
chlorine 4-5 (went down by 1ppm today, but it was 95 or so)
PH 7.6-7.5 (it may went down by .1)
FC 4.5-5
CC .5
TA 130
CH 600
CYA 30-35
 
G

Guest

Numbers look good, CH is a little elevated. I would dump the pucks and use liquid after you finish your tabs. You really need to shock only when your CC goes above .5 or when you drop more than 1ppm of FC on a overnight test. Not sure about the cartridge filters and tabs.
 

Shane1

LifeTime Supporter
Apr 29, 2010
621
Buckeye, AZ 85326
You dont have to backwash with a cartridge which means the only water dilution is splash out, evaporation & rain water. Dilution is how people are keeping thier CYA in check when using the pucks I'm using pucks and I have a cartridge filter. My CYA is about 90 right now. As long as you know the risks of the pucks you can use them all you want. There is mystery of CYA lowering over the winter months but its not clear why that happens.
 

anonapersona

TFP Expert
LifeTime Supporter
Nov 5, 2008
2,598
I don't see your location listed but your current CYA is fine, you could go higher, to 50 easily enough. therefore it is OK to use the pucks if you want to. Given that you have 6% bleach and 12% liquid chlorine in storage, you will want to use them up before too long if it is hot where you are located. The pucks will keep for a long time but the liquid chlorines won't.

I also don't see the size of your pool. You can use the Pool Calculator, at the bottom, Effects of Adding Chemicals, to find out how many of the pucks you can use before your CYA is at 50 which is probably the top of the range you want to be in. Probably, because if you have SWG or are in a very hot area, you may want to go higher on CYA. So find the weight of the pucks you use, and enter Trichlor as the chemical, to see how many oz of trichlor will get you from 35 to 50.

I keep my pucks in a plastic storage shed outside, I couldn't stand to have them in the garage.
 

LeeM2

Well-known member
Jul 3, 2010
96
Pool calc said the 3 tablets would raise my CYA by 4ppm, FC by 6.5, lower PH by 0.35 and raise salt by 5.3

I'm not sure I understand it. Would it affect my water that much regardless of how many holes I have in my floater? I have 3 tablets and 3 holes in my floater and the 3 tablets last about 10 days. Would the tablets devolve faster if I had 6 holes in my floater, affecting my water a lot more?
can someone please explain ?

I guess I don't see a significant change in my CYA because I have been monitoring my CYA for a little over a week.

How can it raise my FC by 6.5 if my chlorine level is less then that?

Also, is it bad to have salt level be raised like that ?

my pool is 22,5k gallons, I'm in NE where we have about 90-95 F lately.

And, you right about the shelf life of the tablets vs bleach. I just wanted to get rid of tablets so that I don't have to smell them all year.

Thanks.
 

duraleigh

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Apr 1, 2007
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Sebring, Florida
Hi, Lee,

This thread seems to have gotten a little off topic. Let's get back to your first question you posted...

1.
I know the pool school mentions that tablets would cause CYA levels to rise and is not a good choice for cartridge filters (I don't understand why cartridge filters. Can someone explain?).
I don't recall that in Pool School....there's no conflict between tabs and a cartridge filter.

2.
Also, 2nd question - I know people here are against shocking pool for no reason. So, is it safe to say that if I keep my chlorine level where it should be (according to CYA\FC chart) I don't need to shock EVER (except when opening the pool I guess)?
Yeah, pretty much. You should shock when there is a reason to shock. You should not shock if there is no need.

Tell us what your water looks like. Are you trying to solve a water chemistry issue or are you just asking about using the pucks?
 

JasonLion

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May 7, 2007
37,880
Silver Spring, MD
Most chlorine tablets are made of trichlor, which raises chlorine, raises CYA, and lower PH. In many cases using tablets, CYA goes up very quickly and becomes a problem well before the end of a single pool season. However, if there is a lot of water replacement, the CYA level won't go up so quickly and it might not be a problem. The most common cause of frequent water replacement is backwashing an undersized DE or sand filter. Cartridge filters don't get backwashed, so pools with cartridge filters have less water replacement and so the CYA level goes up more quickly than it would in a pool with a DE or sand filter. (Note: not all DE filters get backwashed. The no backwash style of DE filter would have the same problems with CYA levels that cartridge filters do. Likewise, we recommend getting a filter that is large enough that it hardly ever get backwashed, which again would cause problems with CYA levels when using tablets.)
 

frustratedpoolmom

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LifeTime Supporter
In The Industry
May 20, 2007
12,223
SWSuburban Chicago, IL
LeeM2 said:
Pool calc said the 3 tablets would raise my CYA by 4ppm, FC by 6.5, lower PH by 0.35 and raise salt by 5.3

I'm not sure I understand it. Would it affect my water that much regardless of how many holes I have in my floater? I have 3 tablets and 3 holes in my floater and the 3 tablets last about 10 days. Would the tablets devolve faster if I had 6 holes in my floater, affecting my water a lot more?
can someone please explain ?

I guess I don't see a significant change in my CYA because I have been monitoring my CYA for a little over a week.

How can it raise my FC by 6.5 if my chlorine level is less then that?

Also, is it bad to have salt level be raised like that ?

my pool is 22,5k gallons, I'm in NE where we have about 90-95 F lately.

And, you right about the shelf life of the tablets vs bleach. I just wanted to get rid of tablets so that I don't have to smell them all year.

Thanks.
That's the overall addition once the tablets have dissolved - but they dissolve slowly so it doesn't happen all at once. CYA levels will go up slowly over a month or so with tablets. More holes the tablets may dissolve quicker.
 

anonapersona

TFP Expert
LifeTime Supporter
Nov 5, 2008
2,598
LeeM2 said:
Pool calc said the 3 tablets would raise my CYA by 4ppm, FC by 6.5, lower PH by 0.35 and raise salt by 5.3

Thanks.
Where I was going with this was that given this info, and the fact that you can go from 30-35 to 50-55 on CYA given the heat, you have about 20 ppm of CYA addition that you can tolerate. So, count out 15 tablets and know that those are all you can use for after that your CYA will be about 55 and you have to stop the tablets then. 15 tablets, no more. If that is 3 a week, then you've got about 5 weeks of tablets to use (plus you will add some bleach).

So, you can keep the floater, keep tabs in it, whether you add more holes or not. Personally I'd keep the floater as it is, no extra holes, as it will insure that your FC never goes to zero while there are tablets in it. Tablets are a luxury that you can afford for now. Later you cannot use them, OK for now; for 5 weeks or whatever. At the end of 15 tablets, then test CYA again, don't bother now you are just wasting tests.

However, the floater alone is not keeping your FC stable. I suggest using the test results daily to begin using bleach to bump up the FC to where it needs to be every evening.

How can it raise my FC by 6.5 if my chlorine level is less then that?
Also, is it bad to have salt level be raised like that ?
The FC from the 3 tablets is a total value over the time the tablets are dissolving. If you smashed them, all would be in the pool at once. Since they dissolve over a period of days, you may be getting 2 ppm of FC per day over 3 days, or 1 ppm of FC over 6 days, depending on how long they take to dissolve. More holes would make this faster but I would leave that alone and treat the tablets as an insurance policy that keeps some FC available slowly. As for the salt, don't worry about that, salt is actually kind of nice as it makes the water feel better. It takes a LOT of salt to get to where it could be noticed, just assume you won't ever get to that point, that'd take many bags of salt.