What am I doing wrong? (CYA)

[TishTash]

As with most, I’m having difficulty with the CYA turbidity test. Using the standard of 50, I see the dot clearly at 50 and disappear around 30. My water is around 70, which tells me it’s actually 90 — not terrible for an SWG pool, esp one losing a lot to UV lately. Still, I wonder what I’m doing wrong. Looking away and glancing doesn’t exactly work because I still see it that way, maybe to 40. Any hints or tips would be appreciated.

1/2: Using standard w/K-2006, at 50.
3/4: Using standard w/TF-100, at 50.
5/6: Using standard w/TF-100 & K-2006, respectively, at 30.

 

[setsailsoon]

Try doing the test outside with the sun behind you.

 

[Stoopalini]

I had the same issue with the standard. The dot never disappeared though, even with the tube full.
In comparison, I have a new pool to which I added 20ppm CYA. I’ve also dissolved about 6 - 3” Trichlor pucks, and the test reads between 30-40 with my pool water.

it seems something is strange with tHe 50ppm standard solution.

 

[Stoopalini]

@TishTash FYI ... here is a thread I started when I was questioning this as well. I thought maybe the standard solution may have a shelf life?

How long do Standard Solutions remain effective? (regarding R-7065 CYA 50ppm Solution Shelf Life)

I ordered a set of standard solutions from tftestkits on Aug 17th, and just today got around to trying out the 50ppm CYA solution, to make sure I'm testing my new pool accurately. I dissolved enough CYA granules in my pool to achieve 20ppm (38oz for my 14,060 gal pool), and when I test the...

www.troublefreepool.com

 

[setsailsoon]

Also make sure you do a full 30 sec of shaking after you add the reagent to the standard solution. Wait a minute and shake 30 sec again just prior to pouring it in the black dot tube.

 

[TishTash]

Also make sure you do a full 30 sec of shaking after you add the reagent to the standard solution. Wait a minute and shake 30 sec again just prior to pouring it in the black dot tube.

I noticed that Taylor states to mix for a full 30 sec, whereas TFTestKits states to mix, wait 30 sec, then mix again. I guess yours is a reasonable hybrid, lol.

I also wonder if using a drop of R-0007 would free up some CYA bound to any Cl, as mentioned on another thread. Worth a shot, I suppose.

Like others, I assumed brightness would render the dot more visible. As someone mentioned in another thread, brightness may make the obscurity brighter, rendering the dot less visible. So out to the sun I go.

 

[TishTash]

Like others, I assumed brightness would render the dot more visible. As someone mentioned in another thread, brightness may make the obscurity brighter, rendering the dot less visible. So out to the sun I go.

Welp, there goes that theory: Outside, with my back to a bright sun, the dot is still markedly visible at 50ppm of the standard, purportedly 50ppm, solution.

I can’t believe some of us are the only ones for whom the standard CYA solution spectacularly fails to work as advertised?

 

[TishTash]

On a related matter: Since with the “standard” (and I use the term very lightly) 50ppm solution, the dot actually disappears around 30ppm for me, is it safe to say that with a given pool sample, whatever level I perceive as the reading should have +20 added to get the actual number?

 

[goody222]

So unfortunately, I ran into the SAME problem a couple of months ago with the "standard" I ordered. I did the test 4 times - indoor, outdoor, cloudy, etc. Got about the same result just above 30 every time. So I went right to the source and ordered directly from Taylor a big bottle of standard (expensive at $20 a bottle + $10 shipping). With THAT standard, I kept getting just under 60!! So then I did more tests with both my new standard the the original standard I ordered. Kept getting 30, 60, 30, 60. So I guess you just can't trust it. (Curious if anyone else out there has done this comparison)

My advice would be to just do the test according to the TFP directions and trust that. The thing that really helps settle my mind is that I don't target a single value - I just shoot for 60-80ppm. I tend to try to stay a little lower in band and don't sweat it if I drop to 50. I'd rather push my SWG a little harder than risk putting in too much CYA, locking up FC and causing an algae outbreak.

 

[TishTash]

I'm linking to the thread referenced by @Stoopalini. Here’s what I discovered once I went through all the permutations of reagents, standards, and tubes:

How long do Standard Solutions remain effective? (regarding R-7065 CYA 50ppm Solution Shelf Life)

I ordered a set of standard solutions from tftestkits on Aug 17th, and just today got around to trying out the 50ppm CYA solution, to make sure I'm testing my new pool accurately. I dissolved enough CYA granules in my pool to achieve 20ppm (38oz for my 14,060 gal pool), and when I test the...

www.troublefreepool.com