Unexplained Replication Transfer Size

All of our offices replicate data every night between SANs (Equallogic PS6100). There is one Replica Set that periodically will have a LARGE transfer size that is unexplained...I'm hoping someone has some insight of what could possibly be causing this? An example of what the size is and what the size should be compared to other replica sets....is as follows. The one is question is SAVPROJECTS....

Replica Set                 Transfer Size

RDUPROJECTS            5.29GB

CHSPROJECTS            39.01GB

ILMPROJECTS              7.01GB

CLTPROJECTS             28.35GB

SAVPROJECTS            167.70GB