hello as I mentioned in the header, My pixhawk 4’s barometer decrease in time. And Altitude goes high when my quad is at the table and steady. Also I am currently trying to use rangefinder and optical flow together. I set EK3 to get altitude from rangefinder but altitude measurement comes from only barometer. I will add a log file and params file. Thank you for your help.
It uses a barometer to calculate height.
Air pressure changes with weather and, with time, the weather does change.
It is only natural that the height will not remain constant.
Thank you for your reply. I will going to use my drone in indoor flight. Because of unstable height, my drone do not stay steady at air. I want to use my rangefinder as a only ekf altitude source. Because of altitude noise in ahrs, local position z value changes so fast. As you can see in the log. I also want to use my rangefinder and of in local positioning if it possible.
It is possible on ArduCopter 4.3dev from today. It can configure the EKF height source
Thank you for your reply and interest again. Where can I get it? I don’t know how to get dev releases. 
Alternatively from Mission Planners Setup>Install Firmware screen. Hit Ctrl>Q and the dev versions will populate.
Thank you guys for your al replies. I will going to update the topic when I overcome the problem 