I remember long time ago I think it was Dante or maybe MassiveG did a write up about what you can do to extra hydrate yourself so you can donate blood. I tried to donate recently and my hemo was in the 19's so I was too high. I drank 2gallons of water daily for 2days and went back and it was still in the mid 19's. I remember in the article it said to take glycerin as well but I cant remember it all. Thanks