I have a Typhoon 3 that is 5+ years old. The TDS is reading 001. It is taking longer to make water and there seems to be more waste water than before. Can you suggest what I need to change out? Thanks.

Darren, if you have not replaced the RO cartridge in 5 years, the cartridge should be replaced. With regular use for replacement water for a reef tank, the RO cartridges are only going to last 18 to 24 months at best. Call me to discuss this RO/DI system.

Actually, ARC member Schwaggs has a RODI that has been in operation for 10+ years with the same membrane. I used the same 100 GPD membrane for 3+ years and only changed it because I switched out to a water saver double membrane 75 gpd unit from another retailer. RO membranes last a lot longer when the input water TDS is soft to start with, as it is in Atlanta. My input water has a TDS of 40.

Darren, I would suggest replacing the prefilters and the carbon block prefilters first, as these clogging will decrease RO production. If you have not replaced the DI resin in the last 1-2 years I would also do that.

Also, lower temperature source water in winter always lowers RODI production. RO production increases as the temperature of the input water increases as the spring/summer months progress. RO membrane product water production rates are temperature dependent.

It could be your membrane, but I think it much more likely to be your sediment and carbon block pre/post filters, and replacing these is a $20 option, as opposed to a much more expensive and possibly unnecessary membrane replacement.