I use a Apera PH and TDS reader and have been confused on the conversion factor from conductivity to TDS. With this model you can set the conversion factor that I understand is anywhere between 0.75 and 0.5 that seems to be on the type of water you are testing? My first unit was default calibrated to 0.71 (that had a fault and was returned) and my replacement set at 0.5 - so what is correct for ratio for testing tap water or aquarium water?
I note that TDS should be used as a base point to monitor and many may not bother testing but my tap water is very hard. If my conductivity is reading 780uS (in one of my tanks) then my TDS is either 585ppm or 390 ppm as a reference point. Looking at many tables online and that I know I have hard water then would I be correct to use 0.55?
My reasoning for knowing my TDS more accurately is using a sterilizer. As the Chihiros Doctor version has a table based on TDS and tank volume. I have seen a thread on this asking advice between this and the Twinstar and I will add a comment there. Basically it states do not use above 500 TDS and reading the table if you have a small tank of 60 litres this reduces to 150 TDS.
I note that TDS should be used as a base point to monitor and many may not bother testing but my tap water is very hard. If my conductivity is reading 780uS (in one of my tanks) then my TDS is either 585ppm or 390 ppm as a reference point. Looking at many tables online and that I know I have hard water then would I be correct to use 0.55?
My reasoning for knowing my TDS more accurately is using a sterilizer. As the Chihiros Doctor version has a table based on TDS and tank volume. I have seen a thread on this asking advice between this and the Twinstar and I will add a comment there. Basically it states do not use above 500 TDS and reading the table if you have a small tank of 60 litres this reduces to 150 TDS.