Is it time to change my membrane?

[yoki32]

Hi guys,

I have a Spectrapure MaxCap® MC-RODI-90 System which I have been using for a year around. I've change the carbon block (0.5 microns) and sediment filters (0.5 micron) at every 4 months.

My TDS meter on the left side in the Out position now shows 0.1 (it usually was at 0.0) and my TDS meter on the right side shows 0.0 on IN and OUT positions.

I do a ~ 4 gallon weekly water change. My system is 29 gallons overall (DT and sump included) and I fill up my 30 gallon RODI water reservoir at about every 2 months.
Is it time to change my membrane? Or can I run longer with it?

 

[mcgyvr]

The RO membrane should last a few years.. 3-5 if you are lucky on average depending on use..

Did you flush and run the system for an hour or so after the new filters? It takes a bit to wash out any "residual" stuff..

I replace the DI resin/filter when I change prefilters..
I don't see that you replaced the DI?

 

[Opus123]

I don't know at which points your tds meters are reading. To really tell you would need to get a tds reading for your tap water and tds reading for the water coming out of the RO membrane. I'm assuming that the .1 in your post is the tds after the membrane. Just based on your usage I would say your RO membrane should last 5+ years. I'm assuming that the right side meter is showing the reading from the 2 DI filters so once they start showing a reading over 1 it is time to change out the DI resin in that filter.

 

[Buckeye Hydro]

Hey Yoki - Assuming you have the DM1 inline TDS meter, it doesn't read in tenths (0.1) so if you take a closer look I think you'll find it is reading 1 ppm rather than 0.1 ppm.

Trace the wires from the meter to the two probes so that you know what sort of water the probe is in. What you should find is:
Left meter:
IN=feedwater
OUT=RO water

Right meter:
IN=after DI No. 1
OUT=after DI No. 2

So neither of the readings on the left meter should be 0.

Typical reading on the left meter "in" would be between 100 and 400 ppm, and
the out would be about 95 to 98% less than that.

So if the IN on the left meter was 100 ppm, the out would be less than 5 ppm.

Russ