low resistance grounding bridges in patch clamp

[christopher del negro]

has anyone had trouble eliminating noise (line frequency) from patch
clamp rigs attributable to faulty grounding with an agar bridge electrode?
	
i have had line frequency problems for about 2 months and have tried many
forms of grounding and only one was successful in eliminating line freq. 
noise: a simple Ag/AgCl pellet (low res.) in the chamber. it seemed all 
agar bridges were too high resistance and allowed noise to enter the set-
up. i have recently constructed large diameter bridges which are a bit
unwieldy in a small chamber such as mine but which apparently have low  
enough resistance to sufficiently ground the preparation and worked well 
for two experiments so far. has anyone else had such a problem?