Recently I bought two digital test meters from China (one for TDS and the other for PH). The temperature displayed on the TDS meter was different from a non-digital thermometer I got from a top fin tank kit. Because of this, I am starting to doubt the accuracy and quality of the TDS meter. Is there any way I could test the accuracy of the TDS meter without RO water? If I do have to get a new test kit, what test kits and brands do you recommend for Caridina shrimp?