Follow the instructions for CYA Testing in Pool School. Read all of the notes in the Pool School article.
Many people find the CYA test to be the most difficult test to interpret and get consistent results.
The CYA test is a turbidimetric test and, the leaset "accurate" of any of the tests in your kit because everyone will interpret "when the black dot just disappears" differently--regardless of techniques and even using the same sample water! That's why there's no need to be specific when trying to get an answer.[1]
Don’t agonize over the CYA test. Just call it as you see it.
Light Conditions Matter For Reading the Dot
As much as possible you should do the CYA test in the same consistent light conditions:
- Outside in full sun or use the brightest indirect indoor light that you can if you have to test at night
- Back to sun
- Don't stare at the dot as you pour
- Fill to a line, hold the tube waist high, and glance at the dot
- If you see the dot fill to the next line and glance at the dot
- When the dot disappears you round up to the previous line. If you saw the dot at 40 and not at 30 then you call it 40
After reading, you can pour mixture back into the mixing bottle and try it again; repeated readings on the same sample will lend confidence in the result.
What the CYA Test Dot Should Look like
The pictures are from Taylor Technologies and illustrate how the dot should look.
TF-100 vs K-2006 CYA Test Differences
The view tube for the TF-100 does use a larger sample size and it goes down to 20 ppm instead of only 30 ppm as the K-2006 does.[2]
It is a bad idea to mix testing reagents and hardware between different testing kits.
CYA Standard Solution
You can buy CYA 50 Standard Solution to practice on and see what the dot should look like at the CYA 50 end point.
Directions for R-7065
1. Fill the red-capped CYA mixing bottle to the bottom of the label with R-7065 (it is the “pool water”). Now, fill the bottle to the top of the label with R-0013 (in 8 oz. bottle).* Mix then wait at least 30 seconds. Mix once more.
2. Next, get the clear tube marked CYA View Tube and holding it at waist level (so you can look down into tube) slowly fill the view tube with the solution you have mixed. Keep filling until you no longer see the black dot in the bottom of the tube. *You should have a reading of 50 ppm, give or take 5 ppm.
Tips
- If the water temperature is below 70F degrees let the water warm up inside before you do the CYA test
