Hi Byork and steve, thank you for your suggestions
Yes i did check the arrangement with short wire near the tank and it was working ok, issue start when i connect the wire in question.
My cat5 is of a good quality single thread copper wire from DLINK, but its 2-3 year old wire exposed in open atmosphere and i doubt it may have build some sort of resistance or something so today i am going to buy a new cat5 and will test it and will post result.