I had a 75 gal empty for 3 months running with HOB. There were some MTS and assassins and sand in there, nothing else. Every week or 2 a few pellets were thrown in. No WC the whole time.
I tested the water before moving fish back in, all seemed well as is. Did a 50% WC anyway and added some extra BB filter from another tank just in case of bio overload. No problems.
I think those BB are pretty tough. Someone once posted an article here on some study about their hardiness.