So I always see some number getting thrown around on the forum about equivalent FC when someone says they have X FC reading and Y CYA. I was wondering about how to calculate that so I searched the forum and found this page:
http://standards.nsf.org/apps/group_public/download.php?document_id=5891
Now I don't know if some better calculation has come along but there the equation is given as:
EFC = 2.06*0.31*(FC/CYA)/(1-(1.8*(FC/CYA)))
Just for fun, I was thinking I could come up with a rough scale factor for each level of CYA to multiple your FC reading and get EFC. Doing this I ended up plotting this CYA vs this scale factor. Then making a trend line of that plot to ultimately come up with a simpler (less accurate) equation.
EFC = 6.8*FC/CYA2
It's especially less accurate down near 20-30ppm CYA. But overall the error ranges between the models from <5% to ~285% and gets you in the ballpark. I was just thinking that WHEN someone on the forum starts asking questions about algae and quoting what they feel are adequate FC levels, this equation could be easily used to inform them about how little actual chlorine there is.
http://standards.nsf.org/apps/group_public/download.php?document_id=5891
Now I don't know if some better calculation has come along but there the equation is given as:
EFC = 2.06*0.31*(FC/CYA)/(1-(1.8*(FC/CYA)))
Just for fun, I was thinking I could come up with a rough scale factor for each level of CYA to multiple your FC reading and get EFC. Doing this I ended up plotting this CYA vs this scale factor. Then making a trend line of that plot to ultimately come up with a simpler (less accurate) equation.
EFC = 6.8*FC/CYA2
It's especially less accurate down near 20-30ppm CYA. But overall the error ranges between the models from <5% to ~285% and gets you in the ballpark. I was just thinking that WHEN someone on the forum starts asking questions about algae and quoting what they feel are adequate FC levels, this equation could be easily used to inform them about how little actual chlorine there is.