CYA from TF100 or K-2005

[engrav]

as per other threads am struggling with CYA dwindles
have K2005 and TF100

CYA with TF100 is between 30 and 40
CYA with K2005 is 50
each done over several times

also
on this site I see CYA error may be ±15 and ±10
super guy at Bellevue PoolPro (no retail just service) says CYA is ±10%
tech support at Taylor email said they give no ± for CYA as individual eyes are so different, just believe the result (sort of a theological test I guess)

so then
do I go with the K2005 value or the TF100 value

 

[jblizzle]

Pick one and go with it. Lighting plays a big role in what result you get and I think I read a thread where someone was comparing the tubes between the 2 kits as they too were seeing different results.

If you want to "know", then order the standard solution (from tftestkits) and see which tube is close to 50ppm and in what lighting.

 

[engrav]

Hi
In fact,
I did that
ordered the 50ppm standard
but oops, ordered from Taylor
oh well
did not order freeze protection as rather pricey
but maybe in July is not freezing at 30000 feet
or maybe it comes ground
but will be fun
or not

 

[jblizzle]

Who said anything about freeze protection?

Are you already using the standard solution? If you have it, then figure out what lighting is needed to get the right value for each tube.

 

[engrav]

has not arrived yet, just ordered yesterday

sorry freeze protection was a joke, poor I guess
when ordering from Taylor a window came up discussing whether or not I wanted freeze protection

 

[Richard320]

I think that's the styrofoam box for shipping it.

Personally, I'd go with the TF100 view tube. It's a lot bigger.

 

[duraleigh]

I chose to use the 20-100 gradation in the TF-100 because it provides a larger sample size and (hopefully) better resolution. I am not sure that is exactly the case but it makes sense........ I do know it is easier to read for us old eyes.

The bigger issue is you are over thinking the problem. Pick one and go with it. What is your Daily FC loss?

 

[engrav]

thank you

I too like and prefer the larger tube. When the 50ppm reference arrives I suspect the large tube will do better.

"over thinking"? You are probably correct. Has to do with personality, how many times round the block, etc. But...

I also think it has to do with the TFP Pool School and PoolMath discussions of CYA behavior and monitoring. For this newbie it was not quite enough.

For example, it says
In the spring, mid-summer, and any time there has been substantial water replacement
Test the CYA level and adjust if needed.
and many threads say the only way to remove CYA is to swap water

so I did a spring summer and was 45 and 30 which PoolMath says is Ok so did nothing
did not think further until pool became a chlorine black hole
then I fell into the CYA quagmire
but am slowly emerging
and is kinda fun

Pool School PoolMath advice, would have been better for this newbie had it said

You can only remove large amounts of CYA by exchanging water (draining, splash, backwash, etc). But it does dwindle away a few ppm q month so...
In the spring, summer and fall test monthly and any time there has been substantial water replacement.
and
CYA testing is turbidimetric and so severely affected by eyes and light. The plus minus error of the test as done by actual persons is unknown and is probably different for every person and lighting condition so don't chase your tail. Just use the same lighting conditions and keep it between 30 and 50. You can purchase a 50ppm reference standard to standardize your method.
and
Tabs will slowly raise the CYA approximately 1ppm per tab.

or something like that
IMO my .02

 

[engrav]

What is your Daily FC loss?

Sorry for slow response but took a few days for stability after adding CYA and turning off the Rainbow

now CYA with TF100 is 30-40 and Rainbow off and heater on and
TA75 CH 260

7/22 FC3 pH7.8 added .5g 12.5%
7/23 4.5 8.0 added 1pt acid
7/24 3 7.6 added .5g 12.5% and 1pt acid
7/25 6.5 7.6
7/26 4.5 7.8 added .5g 5.25% and 1pt acid
7/27 --
7/28 3.5 7.7

so then how would I calculate mean daily FC loss
and
is acid requirement rather normal

 

[timerguy]

The easiest way is to do a late afternoon (30 mins before sundown add whatever chlorine is necessary to get it to the top of the recommended levels for your cya then do another test first thing in the morning before Sunrise do another test at sundown note the difference. Do those tests over several days to determine an estimated average fc loss over a period of time. That's sorta like doing an oclt for several days in a row, hopefully your weather conditions are similar over that time period.

 

[jblizzle]

I think what was meant is to test the pool at the same time each day. Based on what you add/target and what the reading is after 24 hours, that is the daily loss which should be in the 2-4ppm range.

 

[engrav]

thank you x 2

I can do that

but what is wrong with this

all the measurements were at about 7am
during the 6 day period I added 1.2 gallons of 12.5% bleach which is .15 gallons of chlorine
.15 gallons of chlorine is about 5ppm in 30k
since the FC was about 3 on 7/22 and about 3 on 7/28 the 5ppm of added chlorine are gone
5ppm / 6 days is about 1ppm chlorine loss per day
is that not a fair estimate? or have I missed something?

1ppm / day may be low but we have lots of cloudy days

thank you

 

[BillB]

If someone could develop a reliable CYA test they could make a bundle of money.
The dot test is about like reading tea leaves.

I've also found that the standard solution doesn't stay standard.
I got it about three months ago and it read a consistent 50.
Last week it read 60.

 

[pwrstrk]

If someone could develop a reliable CYA test they could make a bundle of money.
The dot test is about like reading tea leaves.

It can be tricky, but practice makes perfect ! There is a 50 ppm comparison test for the TF 100. It gives you a real good idea of what you want to be looking for from what I've heard. I've personally never used it though. ?

 

[jblizzle]

If someone could develop a reliable CYA test they could make a bundle of money.
The dot test is about like reading tea leaves.

I've also found that the standard solution doesn't stay standard.
I got it about three months ago and it read a consistent 50.
Last week it read 60.

That seems unlikely that the solution changed. It is quite inert. More likely that your lighting was different.

 

[engrav]

Greetings

It is time to close out this puzzle and thread.

Puzzle is solved.

Key to solving the puzzle was a comment by jblizzle on 6/15/2012
Keep filling until it stays gone.

If I do that (set the comparator down on a stable surface, add till dot gone, wait a few seconds, if dot reappears add a little more, repeat til it stays gone), and use the 50ppm reference, and round to the nearest 10, I can hit 50 with both 9056 and TF100 almost 100% of the time. Without cheating.

End of puzzle. Thank you jblizzle.

An aside
Even though the technique works with both tubes, after doing many tests of CYA, I can say it is LOTS easier with the TF100 tube. On usability, TF100 tube clearly wins.

End of thread.

 

[duraleigh]

I've also found that the standard solution doesn't stay standard.
I got it about three months ago and it read a consistent 50.
Last week it read 60.

The CYA Standard Solution is a very inert reagent that is simply not affected by much........temp, time, sun, etc.

Both Taylor and TFTestkits warrants the longevity of their reagents by 1 year and 18 months respectively........there's not much that can go wrong with them.

 

[engrav]

Just adding credit where credit is due

I found this post by waste 5/6/2006

quote
Anyway, you've got a couple ?'s, I've got some A's.
Re- cya test. When you or I do the test with the little squeeze bottle, we have to squirt it into the cl test chamber. When we'ree squirting, we are making lots of turbulence and entraining little air bubbles into the chamber, this makes the dot disappear quicker - solution; squirt until you lose the dot, then wait a couple of seconds and see if it reappears - if it does, slowly dribble the mixture down the side of the chamber until the dot goes away (repeat as necessary until the dot stays gone)
end quote