Patent ID: 7947179

Claim:
A method comprising the steps of: a) passing dialysate fluid through a dialyzer; b) conveying the dialysate fluid from the dialyzer to a first housing containing material that releases sodium into the dialysate fluid; c) passing the dialysate fluid through the material in the first housing; d) measuring sodium ion concentration in the dialysate fluid emerging from the first housing; and e) conveying the dialysate fluid from the first housing to a second housing containing material that binds sodium ions from the dialysate fluid; f) directing a portion of the dialysate fluid to bypass the second housing if the measured sodium ion concentration is not greater than a predetermined level; g) passing the dialysate fluid not directed to bypass the second housing through the material in the second housing; and h) conveying the dialysate fluid from the second housing and fluid bypassing the second housing back to the dialyzer.