changing filters in RO unit.

[birdy]

I am getting ammonia reading from my RO unit. I have had it 6 mo. I am assuming I need to change the sediment and carbon filters. My question is, I have a DI resin cartridge and I am not sure if it needs to be changed. How often do most of you change yours. It is supposed to change color when it needs to be changed but I am not seeing any color change.

 

[eseow]

I would say the carbon filters are wasted, but you should NOT be reading ammonia after the RO or even the DI. I would sample water from out of each stage to see what is depleted. Carbon should have removed most of the ammonia, and the RO mainly what is left. After the DI, it should be pure, but the RO & DI rely heavily on the sediment and carbon filters to remove contaminants to avoid fouling the RO membrane or depleting the DI filter. A TDS meter would show how well your filters are performing. Also water pressures will alter an RO membrane allowing contaminant creep.