Need help with RO/DI units

[IPWitan]

I have a Spectrapure mpro unit, 3 stage (not di) with the 60 gal/day output. Someone gave me the unit. The unit was 3 years old, but was told it was barely used. I have used it for a year and made approx 50 gals of water with it.

How do I tell whether it is working? I don't have a TDS meter. I have compared the tap water with the resulting water, and the colors look the same. I live in Swampscott, and the water SEEMS good here, but I don't really know.

CA test was virtually nil for both
PO4 - slightly less phosphate in ro water, but when you are in the 0-.25 range, it is really hard to tell coloring.
Nitrate - virtually nil for both. Again the colors are hard to tell apart at that range.
Alk - result was very low for both.

What tests can I run that would show a difference? I don't have a Cl test. I guess I have a ph test, but didn't test that.

David

 

[coralcor]

you need a TDS meter to tell i believe

 

[pillowfish]

You will most likely not be able to see the difference unless you are pulling in water from the Charles. You either need to get yourself an in-line TDS meter or a hand-held one. They are about $20-25 and worth the piece of mind. Compared to the cost of the unit, the membranes and filters and what you invest in your tank time and money wise, it's an easy investment. YOu can find them at any LFS or at our sponsors such as AWI, BRS, etc.. good luck!