I have noticied that Fresenius changed the bicard/Acid probe filters in the last 6 months or so. The problem is that I am all of a sudden getting black / greyish material in the filters and it's plugging them up in a matter of two months. I have never had this problem before. I am having this happen in all 5 of my units. Any ideas???

I the past I've seen something like this happen. It turned out to be the type of vinegar I was using for the acid rinses. Some of the cheaper vinegar has sediment in the bottom and this was plugging up the filter on the bicarb line.

Thanks for the help, the vinegar was the problem.