Hi all, I'm after a bit of advise for the correct use of a TDS meter for measuring salt for a SWCG pool. Should I deduct my ppm results for CH, CYA, TA and borate from the meters ppm reading?
Having read a few posts around the subject I get the impression that most think that TDS is a bit of a useless parameter to use in a pool since it includes a measure of several different ionic species including calcium, phosphates, nitrates, sodium, potassium and chloride. My phosphates and nitrates are zero or close enough to it and my SWCG runs quite high at 6000ppm.
The test strips aren't particularly accurate. I can't get the Taylor K-1766 hear in Aussie and I've read that it's only accurate to about 200ppm. I have at least 10 pool shops that I know of within a 10km (6.25m) semi circle radius (I'm coastal) and they all use a TDS meter for salt.
I have a HM TDS-4TMA with a range of 0-9990ppm and an a accuracy of +/- 2%. I can only calibrate it to within +/- 3-4ppm. It has a resolution of 1ppm from 0-999ppm and 10ppm from 1000-9990ppm. I finally got myself some 6000ppm standard NaCl solution for calibrating it but at the higher resolution I can only calibrate it to +/- 30-40ppm which isn't the best.