[Simon Carter]

I have an RO with a DI chamber. I have another RO for back up that doesn't, so I added one. The first RO therefore has 3 vertical cartridges of which one is for DI resin. The second also has 3 vertical chambers, but not a DI aspect, hence the addition.
I have previously recharged the DI resin. I've also changed the cartridges & the membranes, but not whilst really knowing why, except that the TDS was creeping up.
My question is if the TDS is up, how do I know that changing the resin is not enough?. How do I know when to change the cartridges &/or the membranes.
Also why the hell isn't there a company out there that offers quality advice on basic issues like this, or is that just my experience?

[Andrew McCann]

Hi Simon

To check whether its the RO or DI that needs attention simply disconnect the RO from the DI, read the TDS out of the RO with a handheld meter then reconnect and read the output from the DI, if it hasn't gone down then its the resin. . Check the output reading regularly from the RO and if it starts to head skywards you need to change membranes or, if you are not doing it regularly give it a good flush ( an hour or so ) and then read again.

Hope this makes sense Simon

Andrew