pH meter, DO meter, electric conductivity
meter, thermometer and so on.
Except the thermometer, there is need to maintain
periodically.
Because if the performance of measure
equipment is bad condition, I can hardly do accurate or proper technical
advises.
As the condition of DO meter was wrong, I changed
battery and internal liquid of the equipment.
As a result, it could be recovered.
However, the work that I put small o-ring in
the sensor by using tweezer was a troublesome task for me, although I could do
easily in my younger days.
Am I presbyopia?
