I have had this 5.5 gal nano setup for about 2 wks now and I used everything from an established tank except the sand but added about 1/2lb of live sand to seed it but I am getting this nasty brown stuff on my LR and on my sand. I used tap water and found out that might be causing this ther question I have is I dont want to spend $100+ on a RODI unit or even a RO unit so I was wondering if I used some type of tap water filter like on of those inexpensive britta filter if that would help or not ? please help and info would be appreciated thanks :eusthink