What is the most accurate CYA test?

[gkl]

For practical purposes I use (and love) the testing supplies in my TF-100 kit. They are certainly accurate enough for general pool-maintenance.

BUT, this question is more of a technical curiosity nature. How would a lab or scientist test the CYA of water if they needed to figure it out to a much higher degree of accuracy.

Why? Well, I'm a tinkerer and was pondering ways to automate the CYA test using a light source, photo-resistive sensor, etc. but realized i would need a better base-line than my own tests if the goal was to improve accuracy as well as automate. I've read of pre-formulated "standard solutions" so that may be my best bet for testing. But, that still left my curious mind asking, "How do they ​know its 50ppl (or 50%, or whatever...)?"

 

[JeanZ1]

My guess would be they would quantify it using a turbidimeter. In other words, a lab person would prepare a series of cyanuric acid standards of differing, known concentrations (i.e. 30, 50, 100), then add the reagent and then measure the subsequent turbidity of each standard. The concentration of the CYA standard is plotted against the turbidity. An unknown sample (pool water) then also gets the reagent added to it and the concentration is read off the previous concentration/turbidity plot.

To do it at home, you would need a good turbidimeter (along with the ability to periodically check/calibrate), and the ability to prepare known standards accurately (requires specialized glassware and measuring tools).

My guess anyway, hope that makes sense.

 

[jblizzle]

Welcome to TFP!!!

There are some systems that try to do as you describe, but very very expensive. Plus, there is just no need to be that accurate. Do your best to read the CYA tube, round up and then you will have adequate FC if you are following the [FC/CYA][/FC/CYA] chart.

The standard is likely made by adding X amount of cyanuric acid to Y amount of water.

 

[JeanZ1]

A turbidimeter could also do double duty as an early warning indicator of an algae bloom, as often the first indication is a cloudy appearance to the water. I've thought of getting one myself but pretty expensive proposition.

 

[Flying Tivo]

Glad you posted, I have an idea of a way to standardize the CYA reading, but dont have the time to do it. Since everybody has a smartphone, i wanted to try and take a picture of CYA standard solution under the normal test conditions and have several members post their pictures and compare. This is more geared towards helping new members figure out the test and be able to share it on the forum. Probably after a few pictures we could probably take an average and have it as a standard way of reading CYA test. If not just tell me im Nuts!

Felipe

 

[gkl]

... To do it at home, you would need a good turbidimeter ...

I hadn't heard of a "turbidimeter", but a quick search reveal several ranging from hundreds to thousands of dollars! Then i saw this ...

Mouser Electronics > All Products
Embedded Solutions
Engineering Tools
Sensor Development Tools
Multiple Function Sensor Development Tools
DFRobot SEN0189

https://www.mouser.com/ProductDetai...FA2asNCLriocmOx1l4X9-rHMsW4QpW3hoCqBwQAvD_BwE

For $10 i may pick one up and see if I can't come up with a working prototype! It's just for fun really. The TF-100 kit is plenty accurate for running my pool.

 

[JamesW]

Cyanuric Acid Portable Photometer - HI96722 - Hanna Instruments

Here is a photometer.

I have also wondered if a uv light and uv camera system would work without reagents if cyanuric acid absorbs uv light.