@alnath Understand the point, there must be common GND between external Power Source, Arduino and the circuit.
@polymorph Thanks for your suggestions. I am now powering off before wiring.
Now. I solved something

I burned that digital temperature sensor which includes an onboard memory.
(This is the second atlas-scientific part i burned)
Fortunately i had another one which is a basic analog model.
I am not using any external power, just using the Arduino for all PH, ORP, DO and TMP sensors.
They worked with the first try!!
Money is not my first concern actually but i am distressed because i don't know how i burned these 2 circuits (EC and Digital TMP).
I used maximum of 9v for the Arduino. And 5v for the external power sources.
Thank you
http://youtu.be/VqUmIBhD2wI