Thomas, I don't know if it's distilled or 'purified'. I have been using water from the same source for about 10 years and have not had this problem until I tried the replenishment route. BTW, I mixed a new batch of D-23 and a new batch of D-23/25 replenisher this week. I'll let you know if there's any difference.
Gerald, If I get the floaters again, I'll try a little Calgon as you suggested.
Thanks to all for your help.