Acceptable TDS Reading for a reef tank

[Razor]

I'm having a nitrate issue and am looking at every part of my system to find out what may be adding to it.

I just installed an inline TDS meter on my RO unit and then realized that I have no clue what I'm looking for. The TDS for the tap water is 110 ppm and the filtered water is 29 ppm.

Is 29 ppm ok for the tank or what should it be?

Thanks.

 

[FB]

I'm not really sure but from what I understand it should be 0.

 

[EmilyB]

It should be zero after RO/DI. An RO unit alone will still leave you a TDS reading. Off the top of my head, rejection rate should be over 90%.

 

[Anonymous]

For me, the TDS is more than 450ppm for the tap, and about 10-20 after the RO. The DI brings it down to less than 0.05 to 0.1 ppm.

You should do better with your, but most TDS meter are not that accurate.

 

[Razor]

I guess our tap water is really good as it never reads over 150 ppm. I don't have an RI unit just RO and after changing the filters am getting a reading of 20 ppm.

Will changing the membrane get me below 20 ppm or is this the best I can expect without a RI unit?

Thanks.

 

[Anonymous]

I have never had a tds reading below 25 from just RO, but then again I have been starting with water in the 500 TDS range. Adding a DI cartridge did the trick to get it down to 2 for me.

 

[Razor]

Where are you guys from with the 450 to 500 ppm tap water.

Isn't that really bad water?

 

[Anonymous]

Southern California. 1/2 from local well water, and 1/4 from Colorado River, 1/4 from Sierra Nevada.

The NorthWest has the better water (softer)