Can rust cause PH levels to fall? I had a few patches I repaired in my faux waterfall feature, areas of which extend below the water line, and wonder if some of the shavings got into the water.
When to Begin Preparing Pool for AZ Summer
- Thread starter asusundevil
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Shavings of metal?
Even if so, no, this won't do it. If they did, you'd want to retrieve them to prevent them staining rust spots on your pool finish.
Even if so, no, this won't do it. If they did, you'd want to retrieve them to prevent them staining rust spots on your pool finish.
Shavings was a bad adjective to use. Dust is more appropriate.
I will be re-testing within the next couple hours and will post the results. Hopefully, my PH is normalized and CYA closer to 50.
I will be re-testing within the next couple hours and will post the results. Hopefully, my PH is normalized and CYA closer to 50.
Today's readings:
FC - 6 down from 7 yesterday
PH - 7.4 unchanged from yesterday
Alkalinity - 130 unchanged from yesterday
CH - 330 first time measurement
CC - 0
CYA - 90 up from 70 yesterday
I can't seem to get my CYA to the 60-50 range. Should I drain some water yet again?
Should losing 1ppm of FC in 24 hours be a concern?
FC - 6 down from 7 yesterday
PH - 7.4 unchanged from yesterday
Alkalinity - 130 unchanged from yesterday
CH - 330 first time measurement
CC - 0
CYA - 90 up from 70 yesterday
I can't seem to get my CYA to the 60-50 range. Should I drain some water yet again?
Should losing 1ppm of FC in 24 hours be a concern?
Losing 2-3ppm of FC a day is normal.
The CYA will not change like that so one or the other test is not correct. Are you pouring the solution back and forth a few times and seeing if you are consistent? Are you doing the test outside in bright indirect sunlight (like with sun to your back) and holding the tube at waist level?
The CYA will not change like that so one or the other test is not correct. Are you pouring the solution back and forth a few times and seeing if you are consistent? Are you doing the test outside in bright indirect sunlight (like with sun to your back) and holding the tube at waist level?
Today I poured the solution back into the viewing tube twice and got the same 90 reading. It was a sunny, gorgeous day in AZ and I stood with the sun to my back while holding the test a little above my waist. Perhaps yesterday's reading was the result of me pouring more of the mixed solution into the viewing tube out of hope. I'm really frustrated by this CYA challenge, esspeciallyy after draining what I thought was half my 28k pool. I write "what I thought" because now I'm beginning to wonder if I didn't drain enough, even though it sure looked half empty/full in my eyes.
Well, that sounds like 90 to me. When I have higher CYA like that after I try the test a couple times, I pour out half the solution and then fill it back up with tap water and try it a couple more times ... should give you half which can be a little easier to discern since the lines are further apart.
I conducted that "extended" CYA test using tap water prior to draining my pool last week and got a reading of 100. I'm in shock that I'm at 90 after the volume of water I drained. I'm going to test it again tomorrow morning before work and immediately after I return. If it's still 90, am I looking at another 50% drain?
Yup. Like I said, do the normal cya test see what you get and then use the same solution diluted with tap water and see if you get about half the CYA level.
Test results today:
Fc - 5
Ph - 7.8
Alkalinity - 130
CC - 0
CYA - 70 (it was very cloudy in AZ today so it's possible I read this wrong)
CYA continues to be the bane of my existence. :-/
Fc - 5
Ph - 7.8
Alkalinity - 130
CC - 0
CYA - 70 (it was very cloudy in AZ today so it's possible I read this wrong)
CYA continues to be the bane of my existence. :-/
Get the FC up 
I would assume the CYA is up around 80ppm and use that for the FC target for now ... err on the high side to be safe.
I would assume the CYA is up around 80ppm and use that for the FC target for now ... err on the high side to be safe.
Get the FC up
I would assume the CYA is up around 80ppm and use that for the FC target for now ... err on the high side to be safe.
After struggling with my CYA a week after draining half my pool, should drain some again? I ask because if I'm going to, I need to start today so everything is done by Sunday.
I'm concerned about my CYA because I dumped two gallons of 10% liquid chlorine on 03/09, tested on 03/10, and my FC was at 7. Now my FC is 5 and Pool Math is telling me to dump an additional 1.5 gallons. That's a lot of liquid chlorine in 1 week, notwithstanding the fact the average temperate in AZ hasn't even reached 90.
It is normal to lose 2-3ppm of FC every day. That is about 1/2-3/4 of a gallon of 10% every day.
Lowering the CYA would actually increase the daily losses due to less protection from the sun.
The higher you raise the FC, the more ppm you will lose in a day.
With a CYA of 80ppm, you need to stay above 6ppm at all times. So everyday you should be raising the FC up to about 9ppm so it never drops below 6ppm by the next day when you add more.
With a CYA that high and the cooler water temps and less intense sun, I would think you should be losing closer to 2ppm a day at normal FC levels.
Lowering the CYA would actually increase the daily losses due to less protection from the sun.
The higher you raise the FC, the more ppm you will lose in a day.
With a CYA of 80ppm, you need to stay above 6ppm at all times. So everyday you should be raising the FC up to about 9ppm so it never drops below 6ppm by the next day when you add more.
With a CYA that high and the cooler water temps and less intense sun, I would think you should be losing closer to 2ppm a day at normal FC levels.
When you write "Lowering the CYA," what do you mean? I ask because some refer to "lowering" as in smaller numeric number; whereas some refer to "lowering" as in where the water line sits within the viewing tube during the test. Example: I say "lowering CYA" in an effort to lower it from 90ppm to a target of 60-50ppm. But as you know, moving CYA from 90 to 60-50ppm actually raises the water line in the viewing tube during the test. Just want to make sure I'm following you.
My second question is this: What is the ideal CYA balance for my 28k pool? Pool Math indicates a 30-80 range, which is a significant variance.
When I say lowering I mean replacing water in your pool to get a lower ppm.
There is no ideal CYA level and it has nothing to do with your pool size.
For a non-SWG pool we say 30-50ppm. For a SWG pool we say 70-80ppm.
It really depends on the amount and intensity of the sun. Here is AZ, with a non-SWG pool, someone may want to raise the CYA to be in the 50-60ppm range, but there is really nothing wrong with being higher yet. The higher CYA only becomes a bit of an issue when you have to SLAM the pool and FC levels get to be very high.
There is no ideal CYA level and it has nothing to do with your pool size.
For a non-SWG pool we say 30-50ppm. For a SWG pool we say 70-80ppm.
It really depends on the amount and intensity of the sun. Here is AZ, with a non-SWG pool, someone may want to raise the CYA to be in the 50-60ppm range, but there is really nothing wrong with being higher yet. The higher CYA only becomes a bit of an issue when you have to SLAM the pool and FC levels get to be very high.
Because I have a non-SWG pool and need to get my CYA from 90ppm to 30-50ppm, do you recommend I yet again drain 40-50% of my pool? Or should I keep things as is and monitor my FC levels very closely?
I suggested before to lower your CYA level to 60. You won't have to drain half of your water to get it from 80 to 60. Pool Math will tell you how much water needs to be replaced to get from 80 to 60.
Now if you choose to leave it at 80 you just have to monitor your FC levels so you don't fall below your min FC level. You don't want to fight an algae outbreak at a CYA level of 80. You want to target your FC at 11 and never below 6 for a CYA level of 80.
Another reason for lowering your CYA is your PH test reads a false high with FC levels of 10 or higher. If you leave your CYA at 80 just make sure you test your PH level when the FC level is below 10.
I checked for you. To lower your CYA to 60 you would need to replace 25% of your water.
Now if you choose to leave it at 80 you just have to monitor your FC levels so you don't fall below your min FC level. You don't want to fight an algae outbreak at a CYA level of 80. You want to target your FC at 11 and never below 6 for a CYA level of 80.
Another reason for lowering your CYA is your PH test reads a false high with FC levels of 10 or higher. If you leave your CYA at 80 just make sure you test your PH level when the FC level is below 10.
I checked for you. To lower your CYA to 60 you would need to replace 25% of your water.
Great feedback, guys. I appreciate you all more than you know.
How do I calculate my target FC level based upon my CYA level?
Pool Math will tell you. Just plug in your CYA level and hit calculate and in the FC column it will give you the range.
I never said you NEED to lower your CYA to 30-50ppm.
It is becoming very clear that you have not read much of Pool School. Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool
Water Balance for SWGs
FC/CYA Chart
It is becoming very clear that you have not read much of Pool School. Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool
Water Balance for SWGs
FC/CYA Chart