My tds meter increases reading with temperature!

[chopficaro]

I Am experimenting with fogponics. I have the fogger right in the reservoir which is also the root chamber, I've heard that is not proper but I think I can make it work. One of the reasons they say it is bad is that it heats up the reservoir. I put 3 foggers in, and the next day my temps went from 73 to 87!!! so i took 2 of the foggers out and only left 1 in. I threw 4 trays of ice cubes in they all melted right away, then just took it over to the ro filter and filled the reservoir up more until the temp was down to 71. I think I can still make this work I just have to use just 1 fogger and put a tray of ice cubes in every day. Here's the weird part: my tds reading went up from 600 to 900 with the temp increase! And went back down with the temp decrease. My tds meter is the HMD ZT-2. WTF!? WHERE CAN I GET A TDS METER THAT WORKS?!?!?