Holding FC at night, but losing a lot during the day

[Pam Jo]

Hi, somewhat new to TFP. Had what I think was ammonia issues in the beginning. Ammonia is now at 0. Did the Slam last week. Thursday morning my FC held without losing more than .5. Pool is very clear and CC is 0.4. CYA is at 35. But I'm still losing so much chlorine during the day!

This morning FC was 3.5. I added 1/2 gal to get it closer to 5, but when I checked, again, that evening it was 0! Added 1 1/2 gal bleach and was at 4.5 an hour and half later. I added 2 gals before bed and FC was 11 this morning at 10am. 12:45pm FC 9, 3:30pm FC 5.

Is this normal? I know the sun will eat at the chlorine, too, but at this rate I'm going to be adding 2-3 gals bleach per day and that won't be trouble free for me.

What could I be missing?

 

[spinPHD]

The higher your FC is above your recommended target the faster your chlorine loss. One way to slow it down is raise your CYA level to 50 and just add enough chlorine to get yourself to 8.

Also, what strength bleach are you using? You may want to find stuff that is 12.5% or 10%

 

[mknauss]

You will lose 2-4 ppm of FC per day without bather load or other organics getting into the pool. Thus if you have six kids in the pool all day it may take twice that amount.
As spinPHD stated raising your CYA abit should help.

Always remember to round up your CYA - your 35 should be assumed to be 40. Follow the FC/CYA chart.

Take care!

 

[Pam Jo]

I'm using 10% and we have had no bathers, yet. Temps have been a little cooler, lately, and water is at 75 degrees.

I probably need to do more reading, still learning. The last two days I've had the pool open, I've lost 7ppm each day. I'm concerned how much I'll lose once it gets warmer and we have more bathers.

I'll try raising CYA to 50 and keeping FC at 8.

Thanks!

 

[spinPHD]

Make sure you also pass the OCLT before raising CYA. You should make sure you don't need to SLAM first by passing the three criteria as explained here:

Pool School - SLAM - Shock Level And Maintain

 

[Pam Jo]

I seem to be holding the overnight OCLT. It's just the daytime that is dropping. I k ew I would lose chlorine, just didn't expect this much. I may call and ask about the oxygenation part of the Ecosmarte that I keep going to see if that affects the chlorine, but I don't think it does. It's just a slower purifier. Also, may try adding diamataceous earth to the filter, as well.

 

[Richard320]

I seem to be holding the overnight OCLT. It's just the daytime that is dropping. I k ew I would lose chlorine, just didn't expect this much. I may call and ask about the oxygenation part of the Ecosmarte that I keep going to see if that affects the chlorine, but I don't think it does. It's just a slower purifier. Also, may try adding diamataceous earth to the filter, as well.

If that Ecosmarte is an ozone system, it depletes chlorine. Straight from Alternative sanitizers and pools--The Truth!!

What about ozone and/or UV? Can't that reduce or eliminate the need for chlorine? In a word, No, and for a very simple reason. Ozone and UV have NO residual effect so again, a residual sanitizer is still needed. The only place these will kill pathogens is in the contact chamber (where the water is exposed to the ozone or UV), not in the pool. Ozone will destroy chlorine but will oxidize organics so it's a two edge sword. You will generally have higher chlorine consumption with ozone than without and it does not allow you to run lower chlorine levels because there is no residual effect from the ozone.

 

[bmoreswim]

Another possibility here is that you are misreading the CYA test and it is lower than you think. This would lead to higher FC loss than expected.

Are you following the instructions regarding doing it in full sun, back to the sun, tube at waist height, don't stare into the tube, look in then look away then back, dot should not be hidden so even Sherlock Holmes couldn't find it.

Also don't forget to stand on your left foot, recite the alphabet backwards and breathe through your nose while thinking about what to make for dinner.

Last four items are optional. Second paragraph is not optional.

 

[Pam Jo]

It's not ozone. I'm not sure the theory, but they are titanium bars that oxidizes the water as it passes thru. I was under the impression that I would need less chlorine to hold the the FC level.

I'll try disabling the unit unit next week and see if it makes a difference.

 

[Pam Jo]

I don't recall the Taylor kit saying I need to do the CYA test in sunlight. Been doing it in my kitchen where I keep my test kit. And I may be making it too technical in judging the dot! I was trying to make sure I couldn't see it all all indoors.

Definitely not doing the last four items! ;-)

Thanks for help!

 

[spinPHD]

Hi Pam,

You may want to check out the Pool School section on best ways to perform each Taylor kit test. I find it easier to understand, and helps answer a lot of question regarding the tests.

Pool School - Extended Test Kit Directions

 

[Akathisia]

Yeah the CYA test results are heavily impacted by light. I bought a 50 ppm standard test sample from TFTestkits and tried it on an overcast day, sunny day facing sun and the recommended back to the sun method and really got a feel for what I should be looking for. Testing indoors would probably skew results depending on light conditions.

 

[Pam Jo]

Ok, I checked CYA outside with the sun at my back. It does make a difference! A little more than 45, so I round up to 50, correct?

The last few days I'm losing between 2-4ppm and I now understand that's normal. Just was hoping I wouldn't have to add bleach every night, but sounds like that is the norm.

I'll add DE to sand filter and tinker with turning off the oxidizer (it's not ozone) and see if that makes a difference. I do feel better using the oxidizer, especially while gone. It's a slow oxidizer, but it does continuously oxidize and I've never had a cloudy pool in the eight years we've had it. But in saying that, I believe adding bleach can make it even better!

Thanks for everyone's help!