T...... colours were a bit bright but I ran put of paper now to experiment any more!
A question about the callibrators....If my exposure is set ok visually and also matches the value of it, how could it be wrong and need callibrating?
I think you have answered your own question to a certain extent. Colour management of the screen is critical and the human eye can be fooled. It's also worth remembering that none of us underwater photographers actually know the real colour of the subjects we shoot is. View a sea urchin with a HID bulb and the colour is different to flash and different again to a tungsten-based source. Take the sea urchin out of the water (no, I am not suggesting you should......) and its under sunlight and the colours changed. Which one is "right"?. Everyone has accepted what colour things should be...but the computer monitor will have it's own ideas and so will the viewer.
Its not just exposure, its the colours represented on screen and "ok visually" might not be quite spot on - what do you have to compare it to? The RAW file? A print?
Think of the number of variables (red, blue, green levels, monitor brightness, ambient light in the room, ink used, paper used.....settings and levels applied by the user in the application, the application itself.....the age of the monitor.....I could go on....) and then try to manage all of these by the human eye. For me, this is impossible. Calibration ensures consistency.
As a first step, ensure the screen you are using can be calibrated. Not all monitors are equal.