Thoughts on bouncing CYA please..

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AussieConcreteClunker

AussieConcreteClunker

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Jan 13, 2019
20
Adelaide, South Australia
Hi brains trust,

ACC here from Aus. We had a FALSE end to summer a few weeks ago, it appears that today will be our last swim in 30C water before the cooler weather settles in and the solar heating fights a losing battle.

After fully appreciating this concept of CYA / Chlorine ratios that TFP is based on, I test my CYA every 2 days.

I have read that levels are only meant to "degrade at a rate of 5ppm a month" or so or when backwashing etc.. but could it be different in Aus? Could there be some environmental / climate reason that my level seems to bounce around?

I use the same lighting (artificial-because I work shifts so I can't test at the same time of the day every time I do the test) stand in the same way / angles etc as I did when I did my standard test (to make sure I was doing it correctly)

I don't backwash much now that I'm on TFP and there has not been much rain here. Is the South Australian climate causing a higher "consumption / degradation" of CYA? 4 weeks ago it was at 90.

How is it possible to go from CYA 40 just two days ago and to now be at 60 having not added anything?

The last fortnight it has been about 40. Some days reading 30 and other days 50 but "stable" enough.

I know the test is highly subjective but after doing about 25 of them since Jan, I thought I had it sorted.

Reagents I'm using now only arrived a week ago so they should be ok.

I do have a Rainbow feeder full of tabs but set to 0. They have not changed size / contributed to levels for the last month or so and I'm not going to dig them all out and try to dispose of them. They can just sit there..

Not a biggie but just wanted to hear people's thoughts?
Cheers
 
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I would suggest that you are testing way too frequently which is both a waste of reagents and time. Your CYA level does not change day to day and you’d barely be able to detect monthly changes unless significant water exchange is occurring. As well, the use of artificial lighting of any kind is a major impediment to the test.

So what you should do is this - test 2 or three times per month when you can actually do the test out in the sunshine of the day light hours, do the test in the same location, and then record that as your CYA. There is no reason to test anymore frequently than that.
 
Just yesterday, I got a 30 point swing of CYA in back-to-back tests using the same grab sample/reagent mix. In my case, it was due to intermittent cloud cover and not holding the tube at waist level. I expected a difference but was surprised by the magnitude. Gentle agitation of the mix bottle before pouring in the observation tube is equally important if the mix has sat at all on your test bench. My method now is 1)stand in the same spot, 2) back to sun, 3) gently agitate, and 4) pour at waist level and record.
 
I found the CYA test very difficult at first and gave ambiguous answers UNTIL I got the 50 ppm standard solution and played around with it until I knew exactly what I was looking for. Now I can do the CYA test and feel very confident if my results. I even sometimes do the 50 ppm standard test right Before I do my pool water test in same position,etc. I’d HIGHLY recommend getting the 50 ppm solution if you don’t have it allready. It’s available from tfttestkits.com.
 
There is nothing special about the Assie or southern Aussie states environment that would cause a variance. The greatest error is testing error, lighting, mixing, sample size, reagent quality etc. Sample collection can affect it also, collecting a sample near top up additions or near where a fresh dose of CYA is being added, these can produce a false positive or negative. Temperature is a factor, direct from Taylor the test sample should be between 50oF(10oC) and 90oF(32oC).
 
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