Fluid Circuit Priming Methods, Devices, and Systems

A method for performing a blood treatment, comprising:

• providing a dry blood filter with a membrane separating a blood compartment and a dialysate compartment;
• flowing a priming fluid into the blood compartment of the dry blood filter and letting the priming fluid flow from the blood compartment, through the membrane, into the dialysate compartment until an entirety of the membrane is fully wetted exclusively from the flow from the blood compartment, to provide a wet blood filter;
• after said flowing until the membrane is fully wetted, connecting a source of dialysate to the dialysate compartment of the wet blood filter and performing a blood treatment that includes flowing dialysate through said dialysate compartment and blood through said blood compartment.