TDS meter reading

[Branew]

I have my own RO/DI unit. Bought it about 6 months ago. Figured it was time to change the filters so I bought new filters and a dual inline TDS meter.

I decided to test the current reading before changing any filters.

Here are my results...

IN: 265 ppm
OUT: 11 ppm

I know the desired output is 0 ppm but is 11 ppm in an acceptable range or should I change the filters now?

Thanks!

 

[RazorbacksFan]

I would say that is acceptable I would change the filter when the output PPM reaches 25.

 

[HN1]

Not shabby at all. I really need to test our's again since the cartridges are a good bit older than last time. Thanks for the reminder!

 

[Kurt_Nelson]

I'd guess your membranes/filters are fine, but you need new DI resin. With good working DI resin, there's no reason your output shouldn't be zero.

If you can, take a sample of water just before the inlet of the DI stage and see what the TDS is. If it's the same as the DI output (11 ppm), then it's time for new DI resin.