does cya change naturally?

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sheloveswater

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May 31, 2009
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The situation is this: I have "shocked" my pool 3 times this season and will soon do the 4th shock. This is getting old and expensive.

As it progressed the opening of the pool has been tedious and frustrating. I am a novice to the BBB method. After shock failure due to bad instructions on the granular pool supply tx, then pump, then broken plumbing, twice; the pool is still dark green. The mechanical failures always happened the day after I started shocking w/ chlorine followed by days before the repair was completed. So I start from square 1 over and over. !)

I do not have my TF100 test kit yet, but it hopefully will be delivered tomorrow. But, in case the kit does not arrive I am wondering if the cya reading of the pool store H2O test from 2 weeks ago would still be valid. The only thing that has been added to the H2O is liquid chlorine bleach.

Before the reading I had increased the alkalinity w/ baking soda and all the other readings were good. My cya at the time was 46 which seems a nice place to start to see what my pool needs in the long run. According to the CH/CYA chart my shock FC needs to be maintained about 18. I understand that should be maintained and checked frequently. So will cya change in 2 weeks, with circulation about 5 days total, lots of CH in 4 days scattered through the 2 weeks in dark pea green water?

Another ? Is it necessary to test, approximately, hourly during the shock tx? I would think adding the CH in the late afternoo PM. My plan tommorrow includes a vacuum with the H2O by/passing the filter which will decrease the amount of pool H2O to be tx'd, then refilling.

I also am hoping that starting the shock in the evening will help reduce the amount of CH lost. My dinky test kit does not display CH over 3ppm. Fedex typically delivers late afternoon, and I am hoping I won't need to test FC during the middle of the night. Then I can start the "real" testing with the kit after studying the inst. the next morn.

I am looking forward to my test kit, but I also really want to open my pool ASAP, it is blazing hot and humid in mid TN right now, 90° tomorrow. I have 20 gallons of liquid CH waiting to tx my pool (I hope it is enough) I have never made it past the is day of chock before I take a giant step backward w/o circulation for days. Aaaaarg! This has got to work!

And my Dad insists I have to use the Baquacil Flocculant he purchased for me, I don't want to use it and I have to prove that I don't need it before he will stop. I told him I would take the products back and return/credit his money. I figured that would make him happy! Even credit would be OK, since I plan to only purchase a useful tool or something cool from the pool store, not chemicals.

I need this to work. Is there an "average" # of days to clear a pool filled with dark green algae? My real queation is "How quickly can I get this done?" I hope someone can make sense out of these ?'s
JoAnne

Edited for line breaks. Butterfly
 
First off, we typically abbreviate Chlorine with CL (or FC for Free Chlorine). CH stands for Calcium Hardness.

Unless you have backwashed or had a lot of rain, your CYA does not typically change much. However, since you are relying on the pool store test, the number may or may not have been very accurate to begin with.

The more often you can test your water and boost your FC back up to shock levels, the faster you will clear your pool. That being said, it is usually more effective to shock at night, so your chlorine is safe from the sun.
 
CYA levels do change over the course of a season, but if you haven't done intentional water replacement they only change rather slowly.

Testing hourly during shocking does speed up the process, but is not required. You must test and adjust the FC level at least twice a day, more often is better.

It can take anywhere from a day to a week to kill all the algae, and then several days to a week for the filter to clear up the water once the algae is dead.
 
Since my last post I have my new test kit :party: I have been using liquid CL wed and thur. The algae is seeming to improve, which is good, but I now have a ? about the cya. On wed evening I added slightly more CL than recommended because the cya reading I was using was from a pool store.

I thought the reading might be too low because the CL I had been using was having little effect on the algae. A good change occurred by thur morn. The test kit came wed evening. I took a reading on thur mid day, after putting enough CL in to raise ppm to 30 the night before, the reading was 10ppm TC, no CC. ph was 7.8, T/A was 70, cya was 65 (I will concede I am not sure about my reading of this test).

I added 6 gal of CL in the late afternoon, then I took readings again of some measurements at 10:00pm, the FC was 20, CC was .5 the cya was now 80. Will the cya increase from 65-80 in a few hours? Or is it my skill in reading that result?
 
No, CYA does not change much, if at all, from day to day. You need to get more practice reading the test result. The CYA test is supposed to be read on a sunny day but without any sunlight shining directly on the view tube. Trying to do the CYA test indoors or in artificial light will give you higher, incorrect, readings.
 
Does anyone have suggestions, clues, advice from common mistakes made doing the cya test? Is the reading accurate when the black dot is barely covered or totally opaque?

It is very inconvenient to have such a high cya right now. I liked it better when I thought it was 45 and not 80. I am going to perform another vacuum to waste to empty the pool some more and clean the floor.

How much H2O should I replace to lower the cya? Is there a calculation or "table" for that? Is it as simple as "replace 50% of the H2O to reduce cya 50%.

My CL numbers seem to be all over the place as well. Thur am 10 ppm, added 6 gal liquid bleach. Thur pm FC is 20 ppm; Fri am added 3 gallons CL, Fri pm 25 ppm, 6 hours later it was 18 ppm. Just this week alone has been 15-1.4 gallons bottles of Clorox so far, last week was a zillion 3/4 gal off brand bottles, the week before was 12 bottles of the 1.4 gal size, the 2 weeks before that was a case of 1 lb apps of granular "shock" and the remainder of last years granular tri-chlor. I am about bleached out!

So tell me it is OK to drain some and then replace the H2O to lower the cya to a more CL manageable place. Plus I really don't want to have to maintain a pool at 6-9 ppm. I am going to change my name to "bleached to death"
 
When I do the CYA test and it's getting to the hard-to-tell stage, I wiggle the tube a little bit and often this lets me notice the black dot (eyes are good at catching motion) and know to put a little more in. Also I do the view-tube part of the test 2-3 times to make sure I'm getting a consistent result--pour the stuff from the view tube back into the mixing bottle and do the black-dot part again.
--paulr
 

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I received my test kit 5 days ago and have used over half of the cya chemical supplied! That is one test that continues to confound me. I seem to be 2nd guessing myself from 80 to 50. "I think I see the dot, but not really, or does a faint outline count or is it an optical illusion?"

I think I see the dot in the Taylor illustration so I don't really trust my judgement or opinion. I hope the reading looks like blinding snow on Mt Everest because it is easier to shock for 20ppm than 31ppm.

At any rate, I emptied about 1/3 of the H2O and refilled to try to get the cya lower, to somewhere between 35-55 according to my ability to see or not see the black dot.

How embarressing, to foul up a test reading because of one's inability to NOT SEE something correctly! "I know when I can see it, I just don't know when I can't see it. (The story of my life...but it could be a good subject for a country song)

This has been so frustrating, I am not sure if I am just losing my mind with stress, or if I have really killed so many brain cells from the CL fumes that I have gone "plum stupid". This is a joke--my pool is not indoors!

I had a FC level of 25 at 8pm after adding 4.2 gl CL. I only lost about 3ppm during the heat of the day from 1pm-8pm. That is a big improvement in the life span of the CL.

I am expecting my results to be 1) H2O losing the green color, hopefully to clear; 2) losing less CL from day to day as the algae dies; 3) the H2O being cloudy (w/o green) before it clears. Am I correct? I will say the pool is significantly less green today than 1 wk ago.

There is hope.
JoAnne
 
Hi JoAnne, yes every day you should see visible improvement.

With the CYA test, rather than waste reagent.... Edit:You can also use half the amount of pool water and half the amount of reagent, mix throughly, then mix that with tap water to get the full normal amount, and multiply the test result by two. End Edit (Thanks Jason!)

or if you want to run multiple tests, use the same sample and pour it back into the mixing bottle. Try the test 2 or 3 times that way and see if you get the same results each time. You will have a +/-10 ppm accuracy with the test anyway, it's very subjective. But the recommended FC levels take that into account.

It's important to do the test in the same lighting conditions every time. For example, don't do it pool side one time and then the next time indoors. Too inconsistent. So indirect light is best, and it may help to have someone give you a second opinion.
 
Thanks for the advice about using less reagent, I am going through the cya stuff like water(Ha Ha) For real, I have less than 30 ml left from my week-old kit.

I have tried redoing the test with the same sample over and over and over. It seems the cya is very important esp when shocking. I started with the pool store reading of 45, which was obviously wrong because nothing happened when I "shocked" the pool using that number.

When I use my new kit the reading is 80! That is a lot of CL! So I drained over 1/3 of the water, replaced it and now my reading is a whopping 70! The first time I tried to shock the pool I drained 1/3 out. That has been 2/3 this season already, for a cya of 70!

I confess to using tri-chlor all last summer, I have used that for years, but always with new water every year. I know it can add cya and this is the first time I have used water from a previous year.

I have noticed that one thing that is throwing my visual evaluation off is that there seems to be a reflection or a glare of some sort in the middle of the water in the tube that appears to be the outline of the dot at the bottom so I add more solution. Then I do it over, etc.

But that just means I would be trying to eliminate that by adding more solution, and if that is my error, then my cya is really higher than what I am reading!

My CL should be extremely stable! Which brings me to this ? I lost 10 ppm CL over a 24 hour period, from 24 to 15. Is this excessive? I am also going through the CL test solution like crazy because the numbers are so high, that is about 30-50 drops each time I test!

I understood that one wants to lose only 1-3 ppm overnight. True?

I hope I can boast of being less frustrated someday like frustratedpoolmom.

I almost wish I had drained it and started fresh. I have replaced 2/3 of the water and spent a fortune on CL. I didn't because I did not want to risk ripping or tearing areas of my rubber coating with the walls moving and the walls will move 2-4 inches when empty and I have corners and seams.

It does look better, but just today I put 2.8 gal of CL in to raise it from 15-23ppm. I feel destined to not open the pool until July 4th, just like past years.

JoAnne
 
sheloveswater said:
Thanks for the advice about using less reagent, I am going through the cya stuff like water(Ha Ha) For real, I have less than 30 ml left from my week-old kit.
Click to expand...
Duraleigh will be happy to sell you a refill!

sheloveswater said:
When I use my new kit the reading is 80! That is a lot of CL! So I drained over 1/3 of the water, replaced it and now my reading is a whopping 70! The first time I tried to shock the pool I drained 1/3 out. That has been 2/3 this season already, for a cya of 70!
Click to expand...
If you drained and refilled 1/3, then drained and refilled 1/3 again, then you've actually replaced not quite 1/2 of the original water. With a CYA that is now about 70, you'd need to replace another 1/3 to get it down to about 50, which is in line with the usual recommendations. Or you can just live with the 70 for this season.

sheloveswater said:
I have noticed that one thing that is throwing my visual evaluation off is that there seems to be a reflection or a glare of some sort in the middle of the water in the tube that appears to be the outline of the dot at the bottom so I add more solution. Then I do it over, etc.

But that just means I would be trying to eliminate that by adding more solution, and if that is my error, then my cya is really higher than what I am reading!
Click to expand...
Try not to have any glare on it when you run the test; not always easy, I know. Outdoors in the shade, or with your back to the sun, is the best lighting for this test. Pouring the stuff from the view tube back into the mixing bottle and trying again is good, I always do it 2-3 times just to be confident of the result.

sheloveswater said:
My CL should be extremely stable! Which brings me to this ? I lost 10 ppm CL over a 24 hour period, from 24 to 15. Is this excessive? I am also going through the CL test solution like crazy because the numbers are so high, that is about 30-50 drops each time I test!
Click to expand...
That's not excessive if you have an algae problem or something else consuming the chlorine. With CYA 70 you won't be losing much to sunlight.

sheloveswater said:
I understood that one wants to lose only 1-3 ppm overnight. True?
Click to expand...
Not more than 1ppm overnight, and CC not more than 0.5 (one drop).

Sounds like things are improving... hang in there!
--paulr
 
This battle has been ongoing for almost 2 months now and I am about to lose my mind. (See history of posts if you dare)

I thought things were improving, I was wrong. Earlier this week the water seemed cloudy, but with a daily green coating on the pool surfaces. I brush daily and vacuum every other day.

My cya is still not making sense to me and now the ph is wacked. For 2 weeks the ph was 7.2-7.6. Today the ph is 8.2! It was 7.2 on 6/24.

On 6/12 my cya was 80. !/3 water change brought it to 70. On 6/17 the cya is 60 using the diluted testing instructions. The same on 6/20. On 6/24 the cya was 20! And I used the last of my cya reagent (almost, not enough for another test). I repeated the test 5 times. I have ordered more.

The FC was 2.5 on 6/25, I added enough for an additional 12ppm last night with a resulting 5ppm in the afternoon today and a very green pool. More green than yesterday. It is very hot here and the pool is 93°.

The only variable I can think of that I have not introduced is a bird issue. I have bamboo (bad idea) next to the pool. Birds (massive amounts) live in the bamboo and I know they poop in the pool because the sidewalk is loaded in poop everyday, so I know some goes in the pool.

The other downside of bamboo, if anyone is interested, is that is sheds immensely into the water, continuously! Then gets into the pump and fouls it because bamboo never softens or decomposes. Plus the bird poop can have tiny (hard as metal) hackberry seeds in it that will go through the pump basket and jam the impeller.

I am sure the bird poop must contribute organic considerations to the pool, but I don't know if it can have any effect on the other chemistry readings.

I have about half of it cut down (so far this week). Not easy since some of it is 0ver 40 ft tall and 2" in diameter.

I am lost, I want my pool even though it is so warm it is like bath water.

Desperate, JoAnne
 
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