Thank you very much Archus!
Purple potatoes seem to be healthier. I have a pack in the fridge, as they were harvested, with a thin film of soil, which the farmer said is best to preserve them together with keeping them in a paper bag. I will use them upon next fast-breaking to get these minerals out of them. I remember them being high especially in phosphorus, among all. I'll probably just slice them in thin pieces and have them raw on day 4-5 maybe. Earlier, if I feel something is off with my electrolytes. Fast wasn't bad. I will do another one pretty soon.
Have a nice Sunday!
DL