Chlorine tabs good idea or not? Says will also lower pH, will lower TA?

Amama

Member
Jun 19, 2017
22
Holden, MO
The previous owners left an unopened 40lb bucket of chlorine tablets and I'm wondering if I should be using those? Says to use 1/week in the skimmer.

So far I'm using 10% liquid chlorine and have to put in about half a gallon each night to keep FC between 4-7. It's always 2.0 after kids swim (CYA 40). I also have to lower pH every other day.
Total alkalinity is high at 180. We have several kids that swim, the splashing is crazy and I thought it would aerate the pool and bring down TA but it hasn't. Would the tablets be a good choice, and will they lower pH and TA?Here is the tablet info:

PoolBrand® 3" Chlorinating Tablets kill bacteria and control algae while reducing pH levels.
Individually wrapped tablets
No blended (no fillers)
Leaves no residue
For all types of pools
Active Ingredient: Trichloro-s-triazinetrione 99%
Inert Ingredients: 1%. Total: 100%. Available Chlorine: 90%.

 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
Sounds like you are a candidate to use them since your CYA is not terribly high. Use PoolMath to figure out how many will add 10ppm of CYA and then stop using them.

Keep an eye on the FC and continue to supplement with bleach as needed.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
Oh, aeration only raises pH, it does not lower TA. Adding acid lowers the pH and TA. And yes the tablets should help to bring those down a little.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,910
San Dimas, CA (LA County)
According to Effects of Adding Chemicals at the bottom of poolmath, each 8 oz puck will add 3.7 Fc and 2.2 CYA. It will also lower pH and TA but those precise calculations are impossible except under really tight parameters.

So... 5 pucks will drive your CYA to 50ish.

And you have already seen for yourself that you use more than 3.7 FC per week. In fact, you use better than 3 ppm per day. So almost a puck a day. You ain't gaining much.

Save them for vacation.
 

Amama

Member
Jun 19, 2017
22
Holden, MO
So I could use the pucks for a little while though until the CYA is around 50? I'm spending a lot weekly on chlorine and muriatic acid, so the pucks might help me get to a more manageable pH and TA sounds like?
 

dsmith99

Silver Supporter
Jun 18, 2016
238
SW, Iowa
I would skip the pucks.

With a CYA of 40 you should be pretty good for the midwest, I have a similar sized pool with a CYA of 40 and add about 50-60oz of bleach per day in this hot weather. I don't really consider that too expensive at all. A gallon of bleach is about $2.60 and lasts around 2.5 days so that comes to around a buck a day, $30 a month, $150 for a whole season. Some folks spend several hundred dollars on each visit to the pool store, several times per summer and they think that is "normal"!

A bucket of pucks only seems cheaper, for all the problems they cause they won't save you anything. If you try to use enough pucks to maintain the higher levels of FC we use at TFP you will burn through a bucket in no time and CYA will climb off the chart. I would save the pucks for times that you are on vacation or gone for the weekend.

If you have a Menards nearby you can grab some 12.5% liquid shock for $1.77 per gallon. Due to the higher strength you will use a little less and that's at a great price. I get about 3 or 4 cases of 4 and store it in my cool basement. You want to buy the freshest you can find and not too much at a time as it loses strength quicker than weaker bleach.

Continue lowering your PH as needed and your TA will come down along with it. When you get TA down to around 80 or so, PH rise should slow down noticably. Make sure you are not trying to lower PH too far. My pool will happily sit at around 7.7 for a couple weeks at a time before creeping up. If I try to lower it below 7.4 it quickly recovers, 7.8 can be just fine if it's willing to stay there.
 

Amama

Member
Jun 19, 2017
22
Holden, MO
Ok, skip the pucks:) We do have a Menards now, I"ll look for the shock you mentioned.

My PoolSchool app has target pH at 7.2. I thought it shouldn't go above 7.4, so that's when I've been adding muriatic acid. Muriatic acid is the more costly thing so far, about 6.00/gallon.

Thanks
 

AftonJeeper

Bronze Supporter
May 11, 2017
1,151
Twin Cities, MN
Ok, skip the pucks:) We do have a Menards now, I"ll look for the shock you mentioned.

My PoolSchool app has target pH at 7.2. I thought it shouldn't go above 7.4, so that's when I've been adding muriatic acid. Muriatic acid is the more costly thing so far, about 6.00/gallon.

Thanks
The "safe"range for pH is 7.2 - 7.8. Read the how to lower TA article. You'll find a point where the pH and TA balance and the pH stops rising so fast. Each pool is a little different so don't worry if your not in the ideal range.