RO/DI water reading at 990ppm TDS

[hashslinging]

My RO/DI water straight from the unit is reading at 990ppm in TDS. I thought the meter might have been uncalibrated, but I recalibrated it and had the same reading. My tap water is reading at 175ppm. Is something wrong with my RO/DI unit? I replaced the filters a few months ago, but did not replace the membrane, could that be the issue? Im still quite new to saltwater so this is very new to me too.

Thank you in advance

 

[KStatefan]

What is the TDS of the permeate coming out of the membrane?

added

Where are you measuring the TDS?

 

[Woodyman]

My RO/DI water straight from the unit is reading at 990ppm in TDS. I thought the meter might have been uncalibrated, but I recalibrated it and had the same reading. My tap water is reading at 175ppm. Is something wrong with my RO/DI unit? I replaced the filters a few months ago, but did not replace the membrane, could that be the issue? Im still quite new to saltwater so this is very new to me too.

Thank you in advance

How did you calibrate the unit? Which unit do you have is it the HM digital meters?

 

[outhouse]

Where are you measuring the TDS?

Agreed.

 

[Reef.]

Sounds as if the waste is getting mixed with the clean water as the waste would be higher TDS than the tap water.

 

[paintman]

If you have Resin 1 and resin 2 cartridges, check and make sure you put them in right side up. I just went through this with my unit. I was getting all kinds of crazy TDS numbers. Turns out I had my cation and anion cartridges in upside down.

 

[BZOFIQ]

Are you testing the brine and not the product?

Is the membrane plumbed in correctly?