RO/DI--people who have it can you help me?

[sharuq1]

Ok so I have my new aquasafe unit setup and it has been up for about a month or so. At first my readings for TDS were 0, but lately they have been slowly climbing. My last reading was at 006ppm. Is this normal? I mean it hasn't been long, I expected the unit to perform optimally for longer than one single month. I have been using about 5-10g per week. Is there something I don't know, or do filters or DI really need to be changed every month??