Old Eheim Trolley Bus question. What voltage? May 14, 2015 18:24:51 GMT 1 Quote Select PostDeselect PostLink to PostMemberGive GiftBack to Top Post by rcvoltar on May 14, 2015 18:24:51 GMT 1 Hi. I just picked up an old Eheim Trolley Bus. I want to test it but do not know what voltage I should use. I do not want to damage it. Can anybody help? Thank you in advance. Jim