Bio Ball Question

[rayjay]

Bio balls don't "retain" nitrates, they just don't process the nitrates to the final stage to remove them from the aquarium so there is a build up in the system.
If the nitrate media is sufficient to handle what is produced in the tank then you have no worries.
If it can't handle things, or if you don't want to use the bio balls and/or nitrate media, then you need to have another form of bio filtration to do the job, like sufficient live rock.
You can't just remove one without having something else to do the job.