trying to figure out chlorine loss

[obryan2579]

So I've been working at this FC loss during the day. Multiple OCLT show zero loss at night with no CC. I know my CYA was original low around 30 and have since bumped it to 40. I had 6 FC loss today from 9ppm to a 3ppm. 7-8 hrs of sun and 90 degrees today. Does running a filter all day make a difference? I run it from sun up to sundown. I don't run it at all at night. Could this be a filtering issue?

My numbers before adding more Chlorine tonight

fc 3
cc 0
ph 7.6
CH- undetectable
Ta 120
cya 40ish

 

[kellyfair]

Just curious why you were at 9, are you coming off of SLAM? How does water look?

 

[Texas Splash]

If you've passed the OCLT and don't see any algae or concerns about algae (cloudiness, etc), then it may simply be time to increase your CYA a bit more for summer now that the temps are increasing and the sun is getting hotter over us. The filter should make no difference, mine is on 24/7 because I'm out in the country. Try a CYA of 50, adjust your FC accordingly, and see how that works.

 

[obryan2579]

Just curious why you were at 9, are you coming off of SLAM? How does water look?

Water looks great. I over shot on my Bleach and it land at 9 last night. Started the morning at 9. I Slammed about 1.5 weeks ago and it went great. All the indicators (other than the FC loss during the day) are that I don't have an algae issue.

- - - Updated - - -

I also went 30 to 40 on CYA with zero change in FC loss. Does it just happen when you hit the right number?

 

[kellyfair]

Could be... try 50 like Tex recommends. Let’s see what that does for you.

 

[funandsun]

So I've been working at this FC loss during the day. Multiple OCLT show zero loss at night with no CC. I know my CYA was original low around 30 and have since bumped it to 40. I had 6 FC loss today from 9ppm to a 3ppm. 7-8 hrs of sun and 90 degrees today. Does running a filter all day make a difference? I run it from sun up to sundown. I don't run it at all at night. Could this be a filtering issue?

My numbers before adding more Chlorine tonight

fc 3
cc 0
ph 7.6
CH- undetectable
Ta 120
cya 40ish

Doubtful it is filtering... I filter 24/7/all season.

I would bump it more, just sounds like your valuable Chlorine is taking a beating from the UV. CYA protects against the UV. Every pool and Sun situation is a bit different, no cause for concern, in fact, it's great that now you know what to do and what adjustments to make. All part of living TFP.

Great job.

 

[obryan2579]

Doubtful it is filtering... I filter 24/7/all season.

I would bump it more, just sounds like your valuable Chlorine is taking a beating from the UV. CYA protects against the UV. Every pool and Sun situation is a bit different, no cause for concern, in fact, it's great that now you know what to do and what adjustments to make. All part of living TFP.

Great job.

thanks for the boost in confidence. Bumping CYA is nerve racking for newbies. I’ve read too many high CYA stories and I’m not wanting to do water changes anytime soon!

 

[funandsun]

thanks for the boost in confidence. Bumping CYA is nerve racking for newbies. I’ve read too many high CYA stories and I’m not wanting to do water changes anytime soon!

Yes, I know that fear too, I am cautious but you already know what raises CYA (Tri-Chlor Pucks OR adding CYA), so controlling that is all there is to it. It can't creep if you are not adding it. So, just keep the increases small, and you will find where you pool is happiest at.

 

[mdogan]

my Fc lost also high. Around 4 to 5. CYA 30.
soon I will increase it. make sure your cya 40 or make sure your pool size is correct.

 

[funandsun]

my Fc lost also high. Around 4 to 5. CYA 30.
soon I will increase it. make sure your cya 40 or make sure your pool size is correct.

I have thought about if 30 wasn't my magic number, how would I do it.

Me being me, I would target a 5ppm CYA increase. My gallons and Pool Math get along (after working that down over time to find that 13,000 works better for me than 13,200). I would bump by 5ppm on CYA, and test for a 3-4 days, and see how that is going, then if I needed another adjustment I would target another 5ppm CYA. I would keep a log. Once I settled on what worked best I would know this for each year going forward and would use it.

 

[tim5055]

The thing it keep in mind when you are trying to track FC loss.... The higher teh FC level, the faster the loss.

As an example..

In a pool with 40 CYA the minimum CYA is 3. If you have the FC at 9 in that pool, 6ppm of the FC (above the minimum of 3) has absolutely no protection from CYA and it can be lost in a couple of hours.

Don't shoot too high and you will conserve FC. If the minimum is 3 and the target range is 5-7, don't chlorinate to 11. You will just loose chlorine needlessly .

 

[obryan2579]

The thing it keep in mind when you are trying to track FC loss.... The higher teh FC level, the faster the loss.

As an example..

In a pool with 40 CYA the minimum CYA is 3. If you have the FC at 9 in that pool, 6ppm of the FC (above the minimum of 3) has absolutely no protection from CYA and it can be lost in a couple of hours.

Don't shoot too high and you will conserve FC. If the minimum is 3 and the target range is 5-7, don't chlorinate to 11. You will just loose chlorine needlessly .

Never thought of it that way, I started this moring with 7ppm with what I’m interpreting to be 50cya now. So that should give me a good baseline of fc loss today. Question: if I’m reading a 50cya 24brs after adding cya in a sock, does that mean I’m protected by 50 or does it still take several days to start protection?

 

[funandsun]

If your test results are 50ppm, then you have 50ppm currently in the water, yes, check back in a couple days but if that is what you targeted and the CYA has been dissolved for 24 hours, in my experience with my pool, you are good to go.

The only thing that can increase CYA is more CYA, whether that is from pucks or stabilizer.

Never thought of it that way, I started this moring with 7ppm with what I’m interpreting to be 50cya now. So that should give me a good baseline of fc loss today. Question: if I’m reading a 50cya 24brs after adding cya in a sock, does that mean I’m protected by 50 or does it still take several days to start protection?

 

[obryan2579]

5pm just retested CYA and FC, started the day at 7ppm, sitting at 4.5 now, 2.5 ppm loss so far during 90+ sun and super heavy pollen. probably 2 hrs of sun left to go. Over shot the darn cya and it’s sitting at 60. I’m done with that. I bumped the fc to get in the range for 60cya. Hopefully this is the happy place