When Ro/DIs go bad...

[TXMike]

So I dusted off my RO/DI unit after about 6 months of non-use. To ensure that the unit was still delivering, I bought a handheld TDS meter from Marine Depot. My tap water tested at 199 ppm, while the water out of the unit tested at 350 ppm! (No, I didn't accidentally test the waste water.)

Is this possible? What's going on?

 

[shag26272]

I think the membrane has to remain wet , did it dry out?

 

[BigEasyReef]

How much water did you let it make B4 you tested it ?

 

[TXMike]

Yes. I left the membrane in the unit in a closet. I had heard once to leave the membrane in a refridgerator for extended non-use, but my girlfriend wouldn't let it happen.

 

[TXMike]

I let it run un-tested for about 20 minutes

 

[BigEasyReef]

I would go ahead & change all the cartridges and start fresh

 

[AZDesertRat]

Before you buy anything test the tap water, RO only without DI and finally RO/DI. Its possible the membrane may still be good and its the DI releasing contaminates since it has lost its electrical charge. It worth a shot.
The RO is the workhorse not the DI yet everyone gets hung up on the DI output, I wish people would understand the DI is simply a final polishing filter and not what does the work. Test the RO only output ALWAYS when you suspect a problem.