CYA of 25 or so-- or is it?

[ZESTR]

So--- last summer my CYA was 100 bc we were new pool owners and used pucks all summer and found TFP in September...
. Now CYA is 25...?
I mean-- we did let a little water out of the pool last fall and got it down to about 60 before winter-- and we are in North Florida (sunny)--but isnt that a big loss in a year?
Am testing wrong?
I put my back to the sun, hold it at bellybutton level... should it be in the shade of my body or should some sunlight be hitting it? When sunlight hits it, I can see the black dot when it's all the way at the top-- I mean it's small but I can make it out. It JUST barely disappears at the very very top. (25?)
If it's in the shade of my shadow, it's more like 30 when I finally cant see it.

I threw a couple of pucks in the floater last week, but no difference in CYA. Have had to add about 5 inches of hose water in the last 2 weeks bc no rain and 88 degree days.

I want a CYA of about 40-- it seems to eat less chlorine at that number.

Am I doing something wrong with CYA?

Here are the rest of my readings from today:
FC= 9
CC= 0
Alk= 75
Cal= 200
pH= 7.6
CYA= 25

 

[jblizzle]

You want the tube in the shadow.

I have no explanation why your CYA dropped so much ... just be glad it did without a very high chlorine demand.

A couple pucks is not going to raise the CYA very quickly in a pool the size of yours. Use the Effects of Adding Chemicals at the bottom of PoolMath to see how much each trichlor tablet is adding.

 

[mikech]

You don't want direct sunlight hitting the tube - you will read low. A couple of 8oz 3" pucks will add 3 ppm CYA according to PoolMath, a small amount that is within the test error range +/- 15. The CYA may not be quite registering yet but should if they are fully dissolved. Evaporation and adding water will make no difference to the CYA number - only backwashing, vac to waste, splash out etc.

My open, screened pool lost only about 10ppm CYA through the winter (Tampa Bay area).

Mike

 

[ZESTR]

This is really weird, guys...

Here are my #s today (lastnight we just added 1 qt of chlorine)....
FC= 9
CC= 0
Alk= 75
Cal= 200
pH= 7.6
CYA= 25

Exactly the same... so... is my CYA actually 25???????

And really-- even in the shade I can still see that black dot.

Is there any chance my CYA testing stuff is bad? I got it from TFPtestkits, though. I got the huge bottle-- 8 oz or whatever that big one is. And I have stored it ina dark air conditioned closet. I bought it in October.

I just cannot explain a CYA of 25 after it was 60 in December...???? Also-- it was just 50 a month ago. We have had to fill the pool maybe 5 inches, that's it.

What is happening!?!? Should I just buy new CYA testing stuff? I was really hoping this 8 oz would last me

I feel like I cannot trust my CYA level and yet FC is holding strong at 9 the last 3 days, so I took the pucks out for now not knowing what to make of it all...

 

[jblizzle]

The reagent is likely fine. Sounds like your CYA is lower than 25 if you can still see the dot.

Do you have an auto-fill on your pool that could be masking a leak?

 

[mikech]

PM me your address and I'll send you enough of the 50ppm CYA standard solution to do a couple of tests if you don't work out what's going on in the meantime.

Mike

 

[ZESTR]

Mike sent me CYA for 2 tests-- it just came, I just did one...
(Thank you SO much!)
It just came and I tested right away-- it's even more clear than the other tests! The other ones were reading JUSt at 30 or maybe a little lower (but it stops at 30)... but this one was like looking straight thru crystal clear water! I don't get it! There is no way my CYA can be zero... 12 months ago it was 100! 7 months ago it was 60 after emptying the pool 1/3 a few times and refillng... I am so confused... the pool looks GREAT-- it's not losing too much chlorine-- about 2ppm per day... like yesterday FC was 9, today it's 7... it's almost 90 degrees each day... I've had trichlor tabs floating in the pool for the last 2 weeks only. I'm going on the guess that my CYA is 30 for pool maintenence. We just SLAMMED and passed OCLT 2 days ago-- now just letting number drift back to a 5 or so...

Emily

 

[jblizzle]

did you get CYA reagent or 50ppm standard solution?

The 50ppm standard solution is used INSTEAD of pool water with the normal CYA reagent so that you can practice and see what kind of lighting and test method makes it read 50ppm.

 

[ZESTR]

Here are the rest of my readings from today:
FC= 7
CC= 0
Alk= 75
Cal= 200
pH= 7.4
CYA= 30?

- - - Updated - - -

Oops-- okay--- so NO pool water--- just mix the CYA Mike sent me with the CYA I have???

- - - Updated - - -

Sorry to bug you all--- can you tell me EXACTLY what to do so I dont waste it?

Mix it with my R-0013 CYA agent for 30 seconds... then dropper it in at waist level, back to sun... hope it reads 50?

 

[mikech]

Cya standard + cya reagent. The standard is your 'pool water'

 

[jblizzle]

Correct. If it is not 50ppm, then you need to adjust your lighting or method of looking at the tube so that is IS 50ppm. Then do your normal CYA test in the same lighting conditions.

 

[mikech]

I checked the standard solution twice before sending, once with the Taylor tube and once with the more accurate (more reagent) tftestkit tube. 50 spot on.

 

[ZESTR]

Success!!!
I kept both solutions and did the tests about 10x each to be really sure.
It was really hard to get the dot to disappear with the 50ppm stuff... after all the tests it seems like my thing is off by 10ppm... so if I kept going til the dot disappeared and then subtracted 10ppm, that seemed accurate. Or-- just going until the dot was very cloudy but not disappeared.
Seems my CYA is 40.
Thank you so much!!!

Today's numbers-
FC= 6.5
CC= 0
Alk= 75
Cal= 200
pH= 7.4
CYA= 40

 

[Scuba_Steve]

Dot should be completely gone.

Tips:

After you do the test, pour the sample back into the mixing bottle and test it again, and again. You can keep repeating the test using the same sample to see if you are seeing the dot disappear at the same level.

Have someone else do the test for you after you try it a few times. See if they get the same result. My 8 year old has very good eyesight and loves testing for me! She nails it spot on every time.

 

[jblizzle]

Then you should have changed the lighting and the way you look at the tube to get it to be 50ppm ... I would not trust arbitrarily subtracting 10ppm.