Most of the time my water source in Vernon is Kalamalka Lake which averages 180 TDS. I recently replaced my 75 gpd RO membrane after flogging the original for a good 6 years. The old one was providing 1 TDS with the Kal Lake water, the new one gets it down to 0 TDS. I still use a DI stage for tank water. Occasionally the city switches me to the Duteau Creek source which is much lower TDS, somewhere around 50 IIRC. Many variables depending on where you live, where your water comes from & seasonal factors. It pays to do a bit of research.

Here in Surrey, we have between 10 and 15 ppm TDS, depending on the season. Spring time is the highest.
With such a low TDS, the filters last a long time. I have at least 5 yrs on the RO membrane.

I'm looking at the AquaFX barracuda on JLaquatics and the Spectrapure 4 stage on reef supplies. Any suggestions on which unit performs better and is a better bang for your buck.

Thanks.