Summer mode = trichlor tabs, Winter mode = liquid chlorine

holdup1time

Well-known member
Jun 15, 2019
77
Houston Texas
So I've been a member of this great site for almost a year now.
I've decided that I'll be running my pool in two different modes...summer mode and winter mode.
I had this idea this winter when I was pumping out 6 inches of water every few months to get my CYA down around 30 to start the new pool season in the spring.
Last year, before finding this site, I was using trichlor tabs and my CYA got to 90....drained some water and got it around 60.
From last July to a month ago, I used liq chlorine and it worked great. Tested regularly and I know what my pool needs.
In the heat of the summer last year, I was having to add at least 1/2 gallon of liq chl to my pool per day....sometimes adding the whole gallon (18,000 gallon pool)
Using the liq chlorine is great because it doesn't affect any of my other test results...CYA stays the same too...which is the best benefit.
However, it did become a little bit of a pain always going to walmart, home depot etc trying to find liquid chlorine.
Over the winter, I had to buy my liq chl from Leslies since none of the other stores carry it except for swim season. And home depot always keeps theres outside so it's not the best quality anyway.
Last month, I was down to my last box of four, 1 gallon, 12.5% liq chl bottles.
My CYA was less than 30....not much but can't accurately tell because the top of the scale is 30 on the device with the black dot at the bottom.
Sooo, I thought this was the perfect time to try my method out....trichlor tabs to get me through the summer season (now to October).
Knowing in doing this, I'd have to test my CYA much more frequently now...since it should start increasing.
What I found is that my CYA was probably too low to start with....was having trouble keeping my FC up...and that was with my inline chlorinator filled with pucks and flow dial adjusted all the way to 5.
Was only running my pump about 8 hours a day...of course could run the pump longer and this would put more chlorine/cya in my pool.
No big deal, still had those 4 bottles of liq chl ...so added a bottle here and there as needed.
Took about 3 weeks and now my CYA is between 30 and 40...and my FC is not evaporating near as fast as it was few weeks ago.
So I plan to keep using the trichlor pucks this summer season for ease of use...can order it online and have it shipped right to the house.
Plan to always keep 4 bottles of the 12.5% liq chl at the house just in case...it's cheaper that buying shock (cal - hypo) and does the same thing.
My CYA will increase all summer season...if I have to drain a few inches here and there I will.
This October/Nov when swim season is over, I'll discontinue the use of the trichlor tabs and go back to liquid chlorine.
This past Black Friday, I caught a half off deal on liq chl so I loaded up....got me through all winter long...except that last box I had.
Pool won't need near as much chlorine in the winter time so using liq chl will be my preferred method.
I'll have Nov-April to slowly drain/fill water to lower my CYA back to around 30 for the following year.
This is what works best for me and my schedule.
The best thing about this site is that I now know my pool and what to expect when using trichlor compared to liq chl.
Honestly my biggest pain in the butt is how fast my Ph increases....my backyard is very exposed to great winds....this aereation though plus pool being new, makes my Ph always increase.
In about 7 weeks, it will be one year for my pool and no algae problems yet :) All I use is chlorine, muratic acid to keep my Ph down, and then Baking Soda to raise my TA back up.
Tested my city supply water and it had CH of 175...so every now and then, I have to add the calcium stuff to keep my CH above 250.
Just thought I'd share this with the site....see some are having trouble finding liq chlorine...nothing wrong with using trichlor tabs if you understand what effect it will have and what you need to do to keep your pool in check.
 

JJ_Tex

Gold Supporter
Bronze Supporter
Jul 17, 2019
2,294
Prosper, TX (DFW)
Pool Size
13000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
You know what the pucks add to your water and are testing to manage it. As long as you continue to test and adjust accordingly, you should avoid the main problem of high CYA as a result of blindly using pucks that we see over and over on here.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,206
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
The biggest struggle is consistently maintaining the FC/CYA ratio as shown on FC/CYA Chart
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,206
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
If your water is cheap you can make it work. When your CYA hits 50 to 60, drain a third to half your pool and refill. Probably every 3 weeks or so. If you are going to get alot of rain, drain down the pool prior and fill up with rain water.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,932
San Dimas, CA (LA County)
That's great that you understand the chemistry and can juggle the parameters. We're not opposed to pucks here if they're used wisely.

I try to save my puck usage for leaving town.
 

DanF

Silver Supporter
Mar 17, 2019
333
Chandler, AZ
Since your city water has such low CH, another option for chlorinating might be Cal-hypo shock in granular form. Lot easier to lug around than liquid chlorine. If you end up using it, I would stop adding calcium.
 

red-beard

Gold Supporter
May 27, 2019
798
Houston, TX
That's great that you understand the chemistry and can juggle the parameters. We're not opposed to pucks here if they're used wisely.

I try to save my puck usage for leaving town.

I use these for when I'm away. They are 3" tables but do not have stabilizer in them. They are not cheap, but are great for when I'm away.

 

Mdragger88

Bronze Supporter
Jun 1, 2018
1,775
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
Like they said test frequently - the issue is usually blind puck usage. With a feeder you may see cya increase faster than u think it will also they can do a number on ph as they are acidic. In the end it may be more complicated than it’s worth- to me the pucks make all my other parameters unpredictable so i just reserve them as fc insurance when i have to be away incase the power goes out & my swg doesn’t run. My cya, ph & alk all stay very steady -aka- low maintenance & that’s how i like it - pucks upset my apple cart. Swg is the way to go for a steady feed of chlorine & low maintenance
 
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Jhick

New member
Feb 20, 2019
3
Cypress, TX
I was just telling my husband I planned on doing the same. My CYA got to 150 after summer last year and it’s back down to 70 since I used bleach all winter, but now that I’m growing tired of the constant addition. Was thinking I’d switch to tablets from a June to Aug and then back to bleach. Testing along the way of course.
 

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JJ_Tex

Gold Supporter
Bronze Supporter
Jul 17, 2019
2,294
Prosper, TX (DFW)
Pool Size
13000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I would try to get your CYA down a bit more before that plan. Hopefully these rains will help you do that before the heat of summer hits.
 

DanF

Silver Supporter
Mar 17, 2019
333
Chandler, AZ
I was just telling my husband I planned on doing the same. My CYA got to 150 after summer last year and it’s back down to 70 since I used bleach all winter....
Your CYA went down just from not using pucks? Thought you had to drain water to reduce CYA.
 

DanF

Silver Supporter
Mar 17, 2019
333
Chandler, AZ
Interesting. My pool approaches 90 degrees in the summer. Maybe that's why I've gotten away with puck usage in the past. Also makes me feel a little better about using pucks while on vacation in the summer.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,206
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Here in the SW desert we can see up to 15ppm drop in CYA during the three main summer months.

If you use just pucks, and even come close to maintaining the FC/CYA levels you should, you are adding many times that amount of CYA per month.
 

DanF

Silver Supporter
Mar 17, 2019
333
Chandler, AZ
OK let me see if I understand. I'm assuming the pool does not have a SWCG:
- CYA can be reduced by either draining or "attrition" (sunlight, high water temp, splashing, evaporation)
- If CYA is low enough, trichlor tablets can be used to provide chlorination while away from the home, provided frequent testing ensures CYA doesn't get too high.
-In the SW deserts CYA attrition could cause the need to add CYA, even if the pool is not drained, especially if liquid chlorine is the sole sanitizer.
- If only trichlor tablets are used as a sanitizer, you will quickly exceed CYA levels, especially if you are using enough tablets to maintain the proper FC/CYA relationship. In this scenario, one would have to almost constantly add tablets, because the CYA would continually rise, causing need for more and more chlorine.
- CH is the only 'attribute' of water chemistry that can be reduced by draining.
 
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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,206
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Pretty much got it. Test your CYA each month from April to October and you will be good.
 
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