When and how often to add liquid chlorine?

Mesamav

Well-known member
Jul 16, 2011
190
Mesa Arizona
I'm a fairly new pool owner. I've been using trichlor the last year but I adjust chlorine levels with liquid chlorine. Usually the 10% stuff.
So I am going to stop using trichlor because it's raising my CYA. I have a sand filter so I do backwash often so over a little time, I should be able to lower the CYA from 65 to a more manageable 40 or so.
Should I add liquid chlorine in the morning or the evening or both? Is there a better time do add chlorine??? How fast does it dissipate?

Thanks
 

Suziqzer

TFP Expert
Sep 21, 2009
914
Greentown, IN
You really need a good test kit to know how much chlorine is needed to safely and effectively sanitize your pool. You can find a couple of recommendations in the pool school section of this site. That will easily tell you how much chlorine is being used up on a daily basis and w/that information and the pool calculator here as well, you will know exactly what you need to add.
 

Mesamav

Well-known member
Jul 16, 2011
190
Mesa Arizona
Thanks for the quick reply.
I do have a test kit and I test first thing in the mornings and many times in the early evenings.
I know how to test but I was just wondering when and how often to put bleach in. Once every day? Split between morning and the evening? Do I just test several times a day and add as needed?
 

linen

TFP Expert
LifeTime Supporter
Jul 30, 2010
8,649
Twin Cities, MN
Mesamav said:
Should I add liquid chlorine in the morning or the evening or both? Is there a better time do add chlorine??? How fast does it dissipate?
Evening is best, as long as you add enough extra so you are still at your recommended FC level (for you cya level) the next night.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
22,069
San Dimas, CA (LA County)
It's all trial-and-error. Let's say you start at 5, add enough to get you to 7, and 24 hours later you're at 4. You didn't add enough; with CYA at 65, minimum FC is 5. You dipped below that. It will only take you a week or two to know your usual consumption. By the way, 65 CYA is not too high if it's real hot and sunny. Knowing your typical consumption, you can get lazy - we all do, eventually. You'll be able to skip testing once in a while and just dump in the usual amount. And you'll also be alerted if consumption suddenly goes up without a good reason, like a pool party with 8 6 year old boys or something.

They key is to add enough to keep the FC above the minimum for your CYA level until you can add more. Pool Calculator is your friend, bookmark it. Big party? Load up 2 or 3 ppm beforehand.
 

Mesamav

Well-known member
Jul 16, 2011
190
Mesa Arizona
While I'm on the subject,
I have a sand filter, I live in the Phoenix area so it gets sizzling during the summer, my pool is in direct sunlight virtually from sun-up to sundown so chlorine consumption probably will be a little high compared to others.
I know you guys frown on using trichlor and I understand the reasons why. It adds CYA. Other than adding the CYA, is there any other reason it isn't good for the water???? I gotta admit, it is terribly easy to use but if it creates other problems as well, I'd like to know because with all the dust around here, I'm constantly backwashing my sand filter. I typically backwash more than I should because the water around here has so much calcium. My calcium level in the pool is in the high 400's and my tap water is 200 so calcium builds up pretty quickly. I lose 1/2 inch of water daily during the summer because the humidity is 15% or less. Our humidity a few days ago was 4%. It doesn't get much drier than that. Add in our typical heat and a little wind here and there and your water goes down pretty quickly.
So there's the story.
With that said, if the CYA stays stable because of how much I backwash, is there other reasons not to use trichlor?

Just curious.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
22,069
San Dimas, CA (LA County)
Mesamav said:
With that said, if the CYA stays stable because of how much I backwash, is there other reasons not to use trichlor?

Just curious.
Nope. I change out a lot of water for CH also, and I'll use pucks to bring the CYA back up. As long as you monitor things, it's okay.
 

anonapersona

TFP Expert
LifeTime Supporter
Nov 5, 2008
2,598
As long as you test and actually KNOW what you have and what you need in the pool, you can manage it any which way that works to keep the levels up. Around here we usually suggest that you keep your chemicals "separate", that is, add exactly as much CYA as you need, then add exactly as much chlorine as you need. But after you get real comfortable with the testing and the Pool Calculator and Effects of Adding Chemicals there and you are aware of the extras that come in various chemicals you can manage it all that way. You will want to keep good notes, however.
You might decide to load 2 trichlor tablets a week in the autochlorinator and add bleach every other day after testing to determine volume needed. You might decide to use only bleach until CYA drops to 30 then use trichlor tablets for 2 weeks while you are out of town, then go back to only bleach until the CYA gets to 45 and then keep it at 45-60 for the heat of the summer. Or you could just use bleach for chlorine and use stabilizer separately for CYA.
I keep a big chart that records test data and all chems added, what I was expecting and notes to myself. During the course of the year I will use mostly bleach, but occasionally trichlor tablets and occasionally cal-hypo powder. The tablets tend to mess with the TA levels and so making that switch can be good or bad, depending on where TA is at that point. As long as you know all the effects of your chemicals, it is OK. Just make notes and pay attention to all the test data. I run a full test each month so that the slower changing things, like TA and CH don't become an issue due to lack of attention when changing chemicals for some other reason.
 

Mesamav

Well-known member
Jul 16, 2011
190
Mesa Arizona
Thank guys for all the info. I've been reading and studying all the stuff on here for the last year. I must admit that last summer I used trichlor exclusively which is why the calcium is a little high and the CYA is a little high. I didn't get a test kit until a few months ago. I can't say why other than I'm cheap.
I'm glad to hear that there isn't anything but chlorine and CYA with trichlor. (Why do they call it TRI-chlor if it only has two things in it? lol.) I can say that now I can monitor my water with a little confidence with my new found knowledge of pool chemicals, what and how they do what they do. I even end up getting into debates with the guys at Leslies. A few days ago the guy at the counter said there was no CYA in their Trichlor and that CYA goes away just like chlorine does. I educated him and I won the debate. He looked it up and finally gave in to my superior knowledge so he was unsuccessful at selling me some of his expensive chemicals. I felt vindicated. I'm no longer connected at the hip to the pool store. When I first got my pool, I was spending hundreds per month to keep it in shape according to Leslies. They loved me there.
Now I go there maybe once a month or less to get chlorine when I'm too lazy to hit Walmart, Lowes or Home Depot.
When I'm in the pool store and here what they are telling customers, it's all I can do to keep my mouth shut. I want to tell them they don't need that, they don't need the other thing either but I keep my mouth shut and cringe at how much they spend to keep things in the clear.