I have almost completed an electronic water color tester ( DIY unit using an Arduino board, LCD display and color sensor ).
Once done, I will need to calibrate it with a few known control samples, so that I can get accurate readings at different levels, and then use these to calculate the reading of the water being tested.
I will be using the local HTH tablets that get dissolved into a set volume of water, and changes color based on the FC level. I have never been very good with comparing the water color to the printed color chart, and I feel that the background light, etc have a great effect on the visualization and personal interpretation of the color - not to mention that everyones eyesight is different.
Once I have this mastered, I hope to be using it to accurately read the pH as well.
So I want to prepare 6 different FC control samples ( 1ppm, 2ppm, etc )
Does the following calculation look correct :
The online pool calculator tells me to add 16g of 65% cal-hypo to 10,000 liters of water to raise the FC to 1ppm.
This makes the ratio :
16g : 10,000 L
= 0.16g : 100 L
= 0.0016g : 1 L
Naturally I want to make a small sample ( 1 L ) for the calibration tests, but I can not simply measure 0.0016g of cal-hypo - too small an amount to measure accurately.
My thinking is :
16g cal-hypo into 1 L ( 1000 ml ) water ( all water used is reverse osmosis water as I assume this should have the least contaminates ).
Ratio is 16g : 1 L
Take 10ml and add to 990 ml water ( to make 1000 ml )
Ratio is now 0.16g : 1 L
Take 10ml and add to 990 ml water ( again to make 1000 ml )
Ratio is now 0.0016g : 1 L
If this is correct, the FC reading should raise by 1ppm for every 10ml of solution added to the 1 L of calibration water.