One of the only noticeable differences between Sustanon and Omnadren seems to be the speed in which estrogen buildup occurs. In comparison, the process appears to be slightly more pronounced with Omnadren . This is of course just a matter of timing, as the slowest releasing ester in Omnadren (caproate) is a little faster acting than enanthate. Blood testosterone levels will therefore peak much faster with this compound, not having the same gradual release time imposed by testosterone decanoate. Users likewise report water retention much earlier into a cycle.