Rookie Challenged by Chemistry

[slperrine1]

Appreciate some feedback on my latest test results, especially as FC and CYA are out of whack, according to TFP ideal levels. New plaster pool with SWG in sunny (mostly) SC. Two months in to maintaining on my own with lots of help from the Pool Math app and TFP School. Got my confidence rattled by these latest results. Thank you!

FC 22
pH 7.6
TA 80
CH 450
CYA 100
Salt 2,800
CSI. -0.22

 

[ajw22]

Yeah, your CYA is high and your FC is high.

What chemicals are you using in your new pool that got you there?

What SWG do you have and what is your SWG % and pump runtime?

Your FC is not way out of wack for your CYA level. You need to lower your CYA by draining your pool to lower both your CY and FC.

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Draining - Further Reading

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[slperrine1]

Appreciate your reply! SWG is a Hayward TCell S340x25. Currently running the pump about 8 hrs/day at 40%. I have only used stabilizer and MA to this point. Using Taylor test kit. How can I safely drain the pool to add fresh water? Terrifying . . .

 

[slperrine1]

8,380 gallon pool. How would I even calculate how much water to drain?

 

[Newdude]

Cya lowers by an even % as it's not naturally in water. To lower half, drain half and refill. (Etc etc)

 

[ajw22]

Is your pool covered?

Running at 40% for 8 hours will give you 1.9ppm of FC/day if your cell is a 325 and 2.7ppm if your cell is a 340.

Reduce your SWG to 20% to let your FC level drop.

Are you doing the FAS/DPD test with a 10ml sample?

 

[ajw22]

Appreciate your reply! SWG is a Hayward TCell S340x25.

Show me a picture of your cell.

Is it a S340 or S325?

I don't know what S340x25 means.

 

[slperrine1]

Is your pool covered?

Running at 40% for 8 hours will give you 1.9ppm of FC/day if your cell is a 325 and 2.7ppm if your cell is a 340.

Reduce your SWG to 20% to let your FC level drop.

Are you doing the FAS/DPD test with a 10ml sample?

Pool is uncovered.

I will reduce SWG to 20% to let FC level drop.

Yes, I am using 10ml sample for FAS/DPD test.

CYA was 65 on 9/3. Pool Math recommended adding 1.5 lb dry stabilizer, which I did. Now CYA is reading 100.

Is it really necessary to drain pool and replenish? Or can I use reduction of FC to address high CYA?

 

[PoolStored]

You should do test here starting at #8. Make sure you are outdoors, sun at your back. Fill to each line. When the dot is obscured, take the number on that line and add 10.

CYA - Cyanuric Acid Test

Cyanuric acid (CYA) is the chemical name for the product commonly called “pool water stabilizer” … Read more…

www.troublefreepool.com

 

[JamesW]

X25 means a 25' cord vs. 15'.

 

[ajw22]

CYA was 65 on 9/3. Pool Math recommended adding 1.5 lb dry stabilizer, which I did. Now CYA is reading 100.

There was no reason to add more CYA when you had a CYA of 70 (we round up).

1.5 lbs of dry stabilizer will raise your CYA by 22ppm and that is exactly what you got.

I don't know what you had the CYA target set at in PoolMath that got you that recommendation. Do not ever follow PoolMath suggestions blindly without doing a reasonableness check. It is only a calculator and will easily send you astray.

 

[JamesW]

TurboCell S3 Salt Cell for 40,000 gallons, 25-ft. Cord​

SKU: TCELLS340X25

 

[ajw22]

Is it really necessary to drain pool and replenish? Or can I use reduction of FC to address high CYA?

You must maintain your FC to at least 12.5% of CYA level to prevent algae. So keep your FC at 13 or above. FC of 20 is ok and you can let it drift down over time.

Biggest problem the high CYA and FC will create is the pH test will be invalid with FC over 10. It will incorrectly read high. Do NOT lower your pH based on the incorrect pH readings.

So you are going to need to jump through some hoops to manage your pH. Easiest is buy an Apera PH60 with calibrating solutions. A calibrated pH meter can give you the correct pH regardless of FC levels.

PH60 Premium Digital Pocket Waterproof pH Meter pH Pen Tester Kit with Replaceable Probe and Backlight-Apera Instruments

The Apera Instruments PH60 Premium Digital Pocket pH Meter / pH Pen Tester is ideal for all kinds of regular aqueous solution's testing, such as hydroponics, aquaculture, pools& spas, water treatment, cooling towers, etc. Can be replaced with ORP probe.

aperainst.com

Otherwise you need to let your FC drop to 10 or below, check your pH, make pH adjustments, then raise your Fc up to 13.

You are getting into the non-swimming season. Your CYA will degrade slowly. You can manage your pool this way until the Spring and then see what your CYA is and if you need to drain then.

 

[ajw22]

X25 means a 25' cord vs. 15'.

Thanks. Never saw that before.

 

[slperrine1]

Pool is uncovered.

I will reduce SWG to 20% to let FC level drop.

Yes, I am using 10ml sample for FAS/DPD test.

CYA was 65 on 9/3. Pool Math recommended adding 1.5 lb dry stabilizer, which I did. Now CYA is reading 100.

Is it really necessary to drain pool and replenish? Or can I use reduction of FC to address high CYA?

Correction: pump is running 12 hrs/day. Please, what is the formula for calculating ppm of FC/day? I missed that in Pool School.

 

[PoolStored]

Please, what is the formula for calculating ppm of FC/day? I missed that in Pool School.

Download pool math, configure your pool. It will help you with additions. Link-->PoolMath

 

[slperrine1]

You should do test here starting at #8. Make sure you are outdoors, sun at your back. Fill to each line. When the dot is obscured, take the number on that line and add 10.

CYA - Cyanuric Acid Test

Cyanuric acid (CYA) is the chemical name for the product commonly called “pool water stabilizer” … Read more…

www.troublefreepool.com

Magic. Clearly, I am one of the novices mentioned. Really appreciate the very specific instructions: back to the sun, etc. tested with this method three times. CYA now showing 80. Thank you

 

[ajw22]

Correction: pump is running 12 hrs/day. Please, what is the formula for calculating ppm of FC/day? I missed that in Pool School.

PoolMath

Effects of Adding

Select SWG as the chemical.

 

[ajw22]

Correction: pump is running 12 hrs/day.

12 hours/day is giving you 4ppm/day of FC. That is more then your pool needs this time of year with that CYA.

Check in a few days and see which way your FC has moved with your SWG at 20%.

 

[slperrine1]

There was no reason to add more CYA when you had a CYA of 70 (we round up).

1.5 lbs of dry stabilizer will raise your CYA by 22ppm and that is exactly what you got.

I don't know what you had the CYA target set at in PoolMath that got you that recommendation. Do not ever follow PoolMath suggestions blindly without doing a reasonableness check. It is only a calculator and will easily send you astray.

View attachment 609668

Lesson learned. Will certainly round up and use “effects of adding” feature in future.