First complete test - High CH

[Tango Zulu]

This is my first semi-complete water test. Pool is about 1 month old.
IG 12000 g plaster

FC: 2.6
CC: 0.2
PH: 7.2
TA: 40
CH: 600
CYA: 55

Not much I can do to lower CH outside of replacing water from what I have been reading. Any other suggestions? Should I take a tap water measurement to ensure there isn't too much calcium in the water before re-filling the pool? Poolmath calculator says I need to replace 42% of the water to lower it to 350.

 

[Texas Splash]

To manage a pool with relatively high CH levels, you'll need to manage pH, TA, and CH together for an optimum CSI level on the Poolmath calculator . When you have time, do this little experiment. Go to the Poolmath calculator and look at the CSI row (3rd from the bottom). Make note of your current test numbers. Now the experiment ... watch that CSI number as you increase or decrease pH and/or TA a bit. Just try it. Watch how quickly that CSI number changes when you let pH and/or TA go up and down. You want that CSI close to zero (neutral). When the CSI gets close to or over .6, you can get scale in your pool, when it gets too low (negative -.6, it can damage your plaster. By managing that CSI number you will do fine. When the next round of FL rains hit you, try to use that fresh water to your advantage, but always keep an eye on the CSI number so you know how to adjust pH and TA. Hope that helps.

- - - Updated - - -

While I'm at it, your CYA is low. For a SWG pool, your CYA should be 70-80 with an FC around 5-6 to avoid getting algae. You may want to jump on that fairly quickly.

- - - Updated - - -

I experimented as well on the calculator, and for your pool, your current numbers show a CSI of about -.57. But if you raise the pH to 7.5 and TA to 50, your CSI goes to -0.1. Jut something to think about.

 

[Tango Zulu]

I understand the FC and CYA values you recommend are what's recommended here but I am still debating if they might not be too high. The Jandy manual for the SWG recommends lower values.

2015-09-28_1109 - CrownImperial's library


http://www.jandy.com/~/media/zodiac/global/downloads/h/h0331400.pdf

I will play with Poolmath and see how TA and PH affect CSI readings.

 

[Texas Splash]

Many times the manufacture's recommendation (equipment, pools, stores, etc) don't take into consideration the CYA/FC relationship. It's a significant problem in the industry. If you do some searching on this forum or the Pool School section, you'll see thorough discussions which clarify how FC and CYA work together (safely) to sanitize the water while protecting the bathers and equipment. Hope everything works out for you. Let us know if you have any more questions.

 

[JVTrain]

You have to decide for yourself what levels you're going to maintain your pool at. The levels recommended here are based on scientific investigation and efficiency of your pool chemistry. The reason TFP recommendations are higher for both CYA and FC maintenance levels is that in Florida, you get lots of sunshine. If you maintain only 20-30 ppm CYA as recommended by Jandy, your SWG will likely not be able to ever maintain enough FC or it will have to run nearly all day at 100% output to do so. However, if you increase the CYA to protect the FC you're producing with the SWG, you can maintain a higher FC with less run time and less output %. It does help that your cell appears to be properly oversized for your pool, but that's no reason to not want to optimize its performance and life.

 

[Tango Zulu]

The Florida sunshine part makes.
How about temperature? Does that affect the CYA and FC levels I should run or is sunshine/UV rays the biggest factor?

 

[Texas Splash]

Temperature can have an effect on FC consumption along with direct sunlight. You'll need to monitor how much FC is being used during the day to see if you are losing too much. We usually like to see a daily FC loss around 2-3 ppm per day (+/- about .5 ppm). When you start losing up around 4ppm or more per day, it might mean that there's not enough FC protection from the sun (CYA too low) or there is algae in the water (even if you don't actually see it). Raising your CYA slightly as recommended above should help protect your FC from the sun and should take some stress off of your SWG. If you find that you are losing too much FC though, or your SWG can't produce enough FC to maintain a good level of about 4-6 ppm during the day, you may have the beginning signs of algae. In that case, you may need to perform an overnight chlorine loss test to check for algae.

 

[Tango Zulu]

Excellent. Thanks.

 

[Tango Zulu]

To manage a pool with relatively high CH levels, you'll need to manage pH, TA, and CH together for an optimum CSI level on the Poolmath calculator . When you have time, do this little experiment. Go to the Poolmath calculator and look at the CSI row (3rd from the bottom). Make note of your current test numbers. Now the experiment ... watch that CSI number as you increase or decrease pH and/or TA a bit. Just try it. Watch how quickly that CSI number changes when you let pH and/or TA go up and down. You want that CSI close to zero (neutral). When the CSI gets close to or over .6, you can get scale in your pool, when it gets too low (negative -.6, it can damage your plaster. By managing that CSI number you will do fine. When the next round of FL rains hit you, try to use that fresh water to your advantage, but always keep an eye on the CSI number so you know how to adjust pH and TA. Hope that helps.

- - - Updated - - -

While I'm at it, your CYA is low. For a SWG pool, your CYA should be 70-80 with an FC around 5-6 to avoid getting algae. You may want to jump on that fairly quickly.

- - - Updated - - -

I experimented as well on the calculator, and for your pool, your current numbers show a CSI of about -.57. But if you raise the pH to 7.5 and TA to 50, your CSI goes to -0.1. Jut something to think about.

Ok. I've been experimenting with this and I am a lil confused.

If I raise PH to 7.5 and TA to 100, the CSI will go down to -0.05 at 550 CH which is what I currently have. If I keep PH at 7.4 and TA at 80 but reduce CH to 350 CSI turns to -0.46.
Does this mean it is better I run the pool at 550 CH with higher PH and TA than lowering CH to 350 while keeping a PH of 7.4 and TA of 80?

The Troublefreepool suggested levels yield a CSI of -0.46. Isn't close to zero supposed to be best?
Not sure I understand.

PoolMath screenshot

2015-10-02_2008 - CrownImperial's library

 

[JoyfulNoise]

Ok. I've been experimenting with this and I am a lil confused.

If I raise PH to 7.5 and TA to 100, the CSI will go down to -0.05 at 550 CH which is what I currently have. If I keep PH at 7.4 and TA at 80 but reduce CH to 350 CSI turns to -0.46.
Does this mean it is better I run the pool at 550 CH with higher PH and TA than lowering CH to 350 while keeping a PH of 7.4 and TA of 80?

The Troublefreepool suggested levels yield a CSI of -0.46. Isn't close to zero supposed to be best?
Not sure I understand.

PoolMath screenshot

2015-10-02_2008 - CrownImperial's library

Typically pH and TA are your two biggest levels for adjusting CSI. So if your CH is high (my CH was 750ppm last time I measured it), then you typically need to operate at a lower pH, TA or both. I keep my TA down at 60ppm and let my pH live between 7.6 and 7.8. Since CH is not easily lowered in most pool (although in yours, you'll see it go down with rain fill), you simply leave your CH as-is and adjust pH and TA.

Realistically speaking, anything between -0.3 to +0.3 for CSI is fine for pools. In a spa where the water temperatures are higher and scaling is more likely, it is better to stay near 0. So find the combination of CH, pH and TA that is easy for you to maintain and gets you as close to 0 as is possible. Since you have an SWG, it is better to maintain a slightly low CSI, -0.1, as that will help with scaling inside the cell.

 

[Tango Zulu]

Typically pH and TA are your two biggest levels for adjusting CSI. So if your CH is high (my CH was 750ppm last time I measured it), then you typically need to operate at a lower pH, TA or both. I keep my TA down at 60ppm and let my pH live between 7.6 and 7.8. Since CH is not easily lowered in most pool (although in yours, you'll see it go down with rain fill), you simply leave your CH as-is and adjust pH and TA.

Realistically speaking, anything between -0.3 to +0.3 for CSI is fine for pools. In a spa where the water temperatures are higher and scaling is more likely, it is better to stay near 0. So find the combination of CH, pH and TA that is easy for you to maintain and gets you as close to 0 as is possible. Since you have an SWG, it is better to maintain a slightly low CSI, -0.1, as that will help with scaling inside the cell.

Thanks, but:

Are you sure you mean you need to lower PH and TA levels when CH is high and not the opposite? When I increase PH and TA in PoolMath is when my CSI comes closer to zero. When I lower PH and TA then CSI increases. At 550 CH with a PH of 7.5 and TA of 100 I am almost at zero at -0.05. If I lower either value CSI goes further into the negative.

 

[JoyfulNoise]

Nope.

If scaling is an issue, then the combination of high pH, high TA and high CH will lead to a positive CSI. If you want to avoid scaling, you keep your CSI negative. If your CH is increasing, as your original post indicated, and you want to maintain the same CSI, then you decrease pH or TA or both. Sometimes those adjustments are minor. The largest contributors to CSI changing is pH and TA.


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