4 stage RO/DI needs changing but which filter(s) ??
 

So my 4 stage RO/DI unit was reading zero on the (handheld) TDS up until about a couple of weeks ago where it started reading 5ppm. I wasn't concerned yet, but last night it read 25ppm. I think now I need to look into replacing some filters but I have to admit I am a bit of a newbie with these RO/DI units. :redface: How do I tell which ones need replacing ? Or do I just replace them all? The whole unit is about 9 or 10 months old so that's how old all the filters are.

All I can tell you is when mine started to creep up on the TDS meter, I replaced the carbon and filter media's (NOT the membrane) and it didn't change much. I then changed the membrane and all was good.

So in my experience the membrane would be it, at least to start. However the other ones are fairly inexpensive, so you can always do them all.

When I started getting a TDS reading above zero I replaced the DI resin and that brought it back down to zero.

Thanks! It almost sounds like I should just replace them all! :lol:

LOL, pretty much. Depending on heavy use or what the TDS is like going in, its probably best you replace all except for the RO. You could just try replacing the carbon and micron filters and see what you get for TDS after that but if its been awhile since you've changed the DI it might be a good idea to change that out too.

so in other words I should/need to change out all my filters! :biggrin:

LOL I guess. I usually start with the canister filters, then check the TDS, then replace the DI if it needs it. Lastly comes the RO if the others don't fix it. No sense in spending the money on a new RO if you don't have to.

Ya good point about the RO. I did read that those should last a while longer than the other resins. Guess that's what I'll be doing this weekend, hunting filters.

Thanks!

Membranes usually last 2 to 3 yrs. I'd change all but the membrane.

My Manual says change the canisters after 6 months and the others after 1 year, course isn't this all dependent on our originating tap water supply quality?