In Center:
(1) Get them to profile the amount of water taken off so that the maximum occurs initially and tails off later in the treatment.
(2) If you do cramp, ask them to stop ultrfiltration whilst you recover from the cramps. It takes five minutes or so.
(3) Set your chair so that your legs are up high (assuming you cramp in your legs).
At home:
I just get up & walk/hobble around. No fix like the in center fix.