A noob question (my 2nd! here!)

The documentation says pull-ups should not be used with analog pins. http://www.pjrc.com/teensy/adc.html

I'm doing an MIDI expression pedal application where one of the available TRS connectors might be unused -- and therefore the pin can drift away from ground -- and generate garbage MIDI messages.

Should I use an external pull-down? If so what value (10K - 50K Ohm seems to be the standard range of expression-pedal pots - so I'm thinking it would have to be fairly large to not affect the output).

I tried it with a huge value (10M) and it worked but took forever to stabilize...

Anyone have any advice before I try to remember how to use Ohm's law or resort to trial and error?