What is the issue with CYA at 80ppm?

[Go_Bluewater]

So last year I had an unexpected algae storm (first in two years) and I ended up here learning all about CYA, liquid chlorine, algaecides, etc. at the time my CYA was around 100/110. (I was a “stuff the chlorinator and be happy” guy before this. Since the closing and opening (and adding water to open) I just tested around 80ppm.

What does the life of a pool owner with 80ppm CYA and using liquid chlorine look like? If I just need to maintain 8ppm chlorine, is there an issue?

(My chlorinator is apparently near end of life, so I’d prefer to switch to a salt water chlorinator when it is replaced) Also, i am on city water so I’d prefer to not drain and refill 10,000 gallons to end up at 40ppm.

Thanks for any comments and experiences.

 

[Jimrahbe]

Go,

You can use any CYA level you want, it just means the higher the CYA level, the higher your FC must be..

I can drain and refill a 17K pool for about $75 bucks.. I can't believe that your water it that much more expensive...

Thanks,

Jim R.

 

[Go_Bluewater]

Go,

You can use any CYA level you want, it just means the higher the CYA level, the higher your FC must be..

I can drain and refill a 17K pool for about $75 bucks.. I can't believe that your water it that much more expensive...

Thanks,

Jim R.

You know, let me go find the water bill and calculate it.

What are the risks of needing an 8ppm FC level? (That’s about the correct number for 80ppm CYA, right?) Is it just potential swimmer discomfort?

 

[Jimrahbe]

Go,

See the Liquid Chlorine selection on this chart for a CYA of 80..

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

Very minimum is 6 and your target should be 9 to 11 ppm,,

It is safe to swim in and no one will even notice.. It just cost a little more..

Thanks,

Jim R.

 

[Go_Bluewater]

Go,

See the Liquid Chlorine selection on this chart for a CYA of 80..

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

Very minimum is 6 and your target should be 9 to 11 ppm,,

It is safe to swim in and no one will even notice.. It just cost a little more..

Thanks,

Jim R.

Thank you.

 

[mgtfp]

As long as there is no algae present in the pool, it is possible to maintain a pool with CYA, enduring the required FC level.

We don't recommend maintaining a liquid chlorine pool at these levels, because the risk is quite high to eventually drop too low with FC and algae creeps in. SLAMming with CYA is another story, that's where draining usually becomes necessary.

Most people with CYA 80 or higher usually find their way here because they ended up with a swamp. And to clear that requires CYA reduction first.

With SWGs we do recommend higher CYA levels. The constant and reliable chlorination reduces the risk of ever slipping too low in FC substantially, allowing to make use of the reduced FC losses to UV and maximise the SWG's lifetime. But should algae ever creep in (due to hardware or user error), then draining is usually required prior to a SLAM.

With a manually chlorinated pool, the risk to benefit ratio is not right to actually recommend maintaining CYA 80. But if you happen to be there and pass the Overnight Chlorine Loss Test, then maintaining the required FC according to the FC/CYA Levels will keep the pool operational.

But stay way clear of the minimum FC, you don't want to SLAM with CYA 80.

 

[Go_Bluewater]

As long as there is no algae present in the pool, it is possible to maintain a pool with CYA, enduring the required FC level.

We don't recommend maintaining a liquid chlorine pool at these levels, because the risk is quite high to eventually drop too low with FC and algae creeps in. SLAMming with CYA is another story, that's where draining usually becomes necessary.

Most people with CYA 80 or higher usually find their way here because they ended up with a swamp. And to clear that requires CYA reduction first.

With SWGs we do recommend higher CYA levels. The constant and reliable chlorination reduces the risk of ever slipping too low in FC substantially, allowing to make use of the reduced FC losses to UV and maximise the SWG's lifetime. But should algae ever creep in (due to hardware or user error), then draining is usually required prior to a SLAM.

With a manually chlorinated pool, the risk to benefit ratio is not right to actually recommend maintaining CYA 80. But if you happen to be there and pass the Overnight Chlorine Loss Test, then maintaining the required FC according to the FC/CYA Levels will keep the pool operational.

But stay way clear of the minimum FC, you don't want to SLAM with CYA 80.

Thank you, makes sense all around. Pool is crystal clear after opening. I’m working the numbers into the optimal range using Pool Math.

If you were in my shoes would you switch to SWG? Would you stand pat with this level CYA then? (On a side note, I got a quote for ~$2100 to install a SWG and it seemed high. What is a reasonable cost to have one installed?)

 

[proavia]

What exact SWG are you considering.
Have you looked into the Circupool RJ series?

Verify your test kit - what is a TF-2005?
Is it a Taylor K-2005 or a TF-100?
The K-2005 is missing the FAS-DPD chlorine test. If you have a K-2005 and add the FAS-DPD test, you have the equivalent of a K-2006.
Update your signature to reflect your test kit.

 

[mgtfp]

I would always switch to SWG. I think that it's not just the most economical way of pool care, but also the most convenient and trouble free way.

When switching, make sure to get a salt drop test and verify your salt level before adding more salt. All added chlorine turns eventually into chloride (which is what a SWG is interested it, it doesn't care about the sodium that comes with salt), so many "non-salt" pools end up after a few seasons with chloride levels that are nearly (or even fully) sufficient to run an SWG.

Blindly adding salt when changing to an SWG can lead to overshooting, and then you'd have to drain because of salt instead of CYA...

 

[mgtfp]

Regarding cost, I'll let others chime in, I can't really speak for the US market.

 

[mgtfp]

I’m working the numbers into the optimal range using Pool Math.

Don't be too focussed on "optimal". Post a full set of test results and we can talk you through what makes sense for you.

But do be focussed on not letting FC slip too low.

 

[fidn37484]

So last year I had an unexpected algae storm (first in two years) and I ended up here learning all about CYA, liquid chlorine, algaecides, etc. at the time my CYA was around 100/110. (I was a “stuff the chlorinator and be happy” guy before this. Since the closing and opening (and adding water to open) I just tested around 80ppm.

What does the life of a pool owner with 80ppm CYA and using liquid chlorine look like? If I just need to maintain 8ppm chlorine, is there an issue?

(My chlorinator is apparently near end of life, so I’d prefer to switch to a salt water chlorinator when it is replaced) Also, i am on city water so I’d prefer to not drain and refill 10,000 gallons to end up at 40ppm.

Thanks for any comments and experiences.

I dream of 80 I’m at 300

 

[mgtfp]

I dream of 80 I’m at 300

Time to drain...

 

[Go_Bluewater]

What exact SWG are you considering.
Have you looked into the Circupool RJ series?

Verify your test kit - what is a TF-2005?
Is it a Taylor K-2005 or a TF-100?
The K-2005 is missing the FAS-DPD chlorine test. If you have a K-2005 and add the FAS-DPD test, you have the equivalent of a K-2006.
Update your signature to reflect your test kit.

Thanks. No details yet on the SWG, I’m open to learn and suggestions.

I’ll update, it was the K-2006, it has FAS-DPD.

 

[Go_Bluewater]

I dream of 80 I’m at 300

What are you doing to manage that?

 

[fidn37484]

What are you doing to manage that?

Pool service people dichlor tricolor products I didn’t know any better at the time. Thought they knew what they were doing. I’m going to drain it. Tough to resist those snake oil products that remove cya. Clever evil ******* who came up with those.

 

[Go_Bluewater]

Don't be too focussed on "optimal". Post a full set of test results and we can talk you through what makes sense for you.

But do be focussed on not letting FC slip too low.

I’ll be testing again to confirm TA and CH but here’s where I stand after opening. (They put a case of chlorine in, I didn’t catch the %)

======================
Latest Test Result Summary:
FC: 19.5 (2 days ago)
CC: 0.0 (2 days ago)
pH: 7.5 (2 days ago)
TA: 90 (2 days ago)
CH: 240 (2 days ago)
CYA: 80 (2 days ago)
TEMPERATURE: 72° (2 days ago)
CSI: -0.34 (2 days ago)
================================

 

[mgtfp]

That's not a bad place to be - apart from CYA
If your pH is stable, then there is nothing wrong with TA 90. If your pH tends to rise quickly, then you can reduce that a bit, but it will do that pretty much on its own each time you add acid when pH gets too high.

Your CH is absolute fine for a fibreglass pool. Do you have a waterline tile with cement based grout? But even then, your CSI is fine. If you decide to maintain lower TA and have cement based grout, then I would consider bringing CH up to maybe 300.

But this also depends on your fill water and how much rain do you get. It's helpful to test CH and TA of your fill water to get an idea if TA and CH get a bump each time you replace evaporated water (that leaves TA and CH behind) with water that's adding fresh TA and CH.

 

[Go_Bluewater]

That's not a bad place to be - apart from CYA
If your pH is stable, then there is nothing wrong with TA 90. If your pH tends to rise quickly, then you can reduce that a bit, but it will do that pretty much on its own each time you add acid when pH gets too high.

Your CH is absolute fine for a fibreglass pool. Do you have a waterline tile with cement based grout? But even then, your CSI is fine. If you decide to maintain lower TA and have cement based grout, then I would consider bringing CH up to maybe 300.

But this also depends on your fill water and how much rain do you get. It's helpful to test CH and TA of your fill water to get an idea if TA and CH get a bump each time you replace evaporated water (that leaves TA and CH behind) with water that's adding fresh TA and CH.

Thanks. This is a full fiberglass pool, all the way up and around the lip. Great tip on taking measurements on the fill water! I assume alkalinity, CH and solids all remain as water evaporates so if I have high measurements in any of them they will raise with filling?

Last year my ph kept falling, but that’s a function of the tabs, right? I’d really like to get the SWG, is it something a reasonably handy person can do?

 

[mgtfp]

Thanks. This is a full fiberglass pool, all the way up and around the lip. Great tip on taking measurements on the fill water! I assume alkalinity, CH and solids all remain as water evaporates so if I have high measurements in any of them they will raise with filling?

Last year my ph kept falling, but that’s a function of the tabs, right? I’d really like to get the SWG, is it something a reasonably handy person can do?

Great, then you don't have to worry about CSI being too low (only about pH being too low, this applies everywhere, especially where metal is involved, e.g. in heaters). But you still don't want CSI to be too positive, scaling can happen on every surface. Should you change to an SWG, then you want CSI slightly negative to avoid scaling inside the cell.

Yes, trichlor tabs constantly pull down pH and TA, requiring frequent baking soda additions.

This pH-pull (over-) compensates in Trichlor pools the pH-rise due to CO2-outgassing. Pool water is oversaturated with dissolved carbon dioxide that keeps constantly outgassing, driving pH up in the process. Like an opened soda bottle, basically.

That's why liquid chlorine and SWG tend to have rising pH, which has noting to do with the liquid chlorine. Liquid chlorine temporarily raises pH after the addition, but once the added chlorine is used up, pH is down to where it started (+ rise due to CO2 outgassing that happened in the meantime). The complete chlorination cycle with liquid chlorine (and SWGs) is pH-neutral.

That's why we recommend lower TA with liquid chlorine and SWGs. Lower TA means less carbonate in the water and less CO2 outgassing. And because we don't keep adding acid as part of adding chlorine, we don't need that much buffering.

With Trichlor on the other hand, you do need higher TA to have sufficient pH-buffering, and you actually want this CO2 outgassing to happen to actively counteract the Trichlor's pH-pull, and not just buffer it.

Installing an SWG is easy. I'm probably the wrong person to talk about SWGs available in the US, but I'm sure that @Jimrahbe and @proavia will chime back in with good advice and recommendations on that.