looking to buy a TDS meter

Wow, I don't know. Honestly, when I got a reading I just took it at face value. 500ppm is unsafe drinking water according to the directions I got. My tap is 182ppm pretty consistant. The water in my RO garbage can is 3ppm. The water I last picked up from the store's RO machine was zero.

So, even if it is an approximate value, it gives you a good idea of what you are facing comparitively. I wouldn't worry about it. With anything there is going to be a measure of inaccuracy, and unless you are willing to spend big bucks, it is something that you'll have to let go......I know I have opted for the inexpensive TDS and Refractometer. And I am happier than a clam with them.

 

That's the way I understand resolution. I agree that it is kind of crappy.

That said the BulkReefSupply one that pharmrjohn linked does have a resolution of 1ppm and is about the same price. Here's a link directly to the site, although it looks like it's about 50 cents more expensive on their site but maybe some of that is due to ebay fees or something? I don't know I've never bought anything off ebay.

http://www.bulkreefsupply.com/RO/DI-Filters-&-Systems-RO/DI-Accessories/c9_11/p594/TDS-3-Handheld-Meter-With-Carrying-Case/product_info.html

 

TDS-EZ Water Quality Tester - HM Digital

This is the one I use. Haven't had any problems with it so far.