i have no safe gaurds in place for mine....i have a tunze and a koralia...the only time my nem ended up in the koralia was when it was very unhappy with current living arrangements...just maek sure your water is pretty much perfect, the flow is really good and erratic, and that the lights are sufficiently strong...he shoudl stay where you put him...
that said people have used the "needle point" mesh found at walmart in the fabric and sewing section to make a box around the PH until the nems settle down..