I'm working on a project where we will present the user with a grid of rows, each of which has a value that's too high or too low (a value associated with the row is higher or lower than the range it's supposed to fall in, and the user will take actions from there).
I want a visual way to represent at a glance which rows are too high and which are too low, but I'm not sure how exactly.
The original requirement specifies that a green "up" arrow and a red "down" arrow be used, but green and red have a good/bad, go/stop relationship. Both states in this list (too high and too low) are bad, so I'm afraid that having one be green would be confusing.
I had the idea to go with blue and red, similar to how Outlook represents high and low importance, but again red indicates "bad", but "blue" is also bad in this context.
Last idea I had would be to come up with an icon with both up and down arrows next to each other, with one being filled-in or highlighted and the other being faint/disabled, but another requirement is that the end user can filter out all the highs or all the lows (but not both) so having nothing but enabled arrows in one direction and disabled arrows in another direction might be pointless.
How should I represent "too high" and "too low" with icons and/or colors?