I just wanted to pass on some information I found. Probably obvious to most but it could save some money. No need to purchase calibration solution.

1mg of solute per 1L of water would equal 1ppm. So to get a 2Kppm solution would need to put 2g of salt into 1L of purified water.. or just put 1g of salt into .5L of purified water. The water MUST be purified, pure water has almost no conductivity, compared to tap water which has all sorts of contamination (tapwater here reads about 80ppm). So get some distilled water for this.

Once you have the 2K solution from 1g into .5L, you can put some of that in a jar, the pour out the rest till you have only 250ml, pour in purified water till you get 500ml again, then you have 1000ppm! Keep doing this if you want to create a range of solutions, just be careful to measure perfect and STIR IT UP WELL.

Taken from: PPM on a Budget. They also talk about how to make your own TDS reader to save a few bucks.

-Cheers-
Champ

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Always good to know. Thanks. I just keep checking my R/O water, it's at 0ppm's. When that changes I recalibrate.