Problems with RO/DI unit and TDS

Hey everybody, this is my RO/DI unit...

http://www.amazon.com/Coralife-05692-Pure-Flo-50-Gallon-System/dp/B0006JKO9W

Long story short, life crept up on me and I didn't do a good job of keeping up with checking the TDS of the water coming out of my unit. When I finally did check it, it came out to 28 ppm. My tap comes out to about 145 ppm.

I went ahead and bought all new pre filters and replaced them. Did not bother to replace the membrane because the manual says its good for 2-3 years or 12k-18k gallons. But after replacing all the prefilters and letting the unit run for about 20 minutes, it still came out to 27 ppm. How is this possible?

I started using this unit about 9 months ago, everything was new. Could the fact that i didn't change out the pre filters right when the tds started creeping up from 0 cause my membrane to become bad before the 2-3 years or 12k-18k gallon guideline?

TL1000RSquid said:

So you replaced the sediment and carbon block correct? What about the DI resin? If all was replaced maybe just need to let it run longer being only 50gpd.

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Yes, the sediment, carbon block, and DI resin was all replaced. So far Ive made about five gallons and its still 27 ppm, I guess Ill do another 5 and see what happens?

TL1000RSquid said:

After 5 gallons it should be plenty flushed. The membrane should still be good as well. Is it possible during the filter changes a couple hoses got replaced in the wrong connectors? The only other possibility I can think of is maybe the TDS meter is in need of calibration.

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Just checked the connections, everything seems to be right. One thing I noticed is that the hose connecting the carbon block to the membrane housing only has a flow restrictor(I think thats what its called, its a little white piece that sits inside of the tube just before it connects to the next section) on the side that connects to the membrane housing. There isn't on the side of that same hose that connects to the carbon filter.

I'm doubtful that this is the reason, but I'm stuck otherwise.... Im almost im at the point where I feel like saying screw it and just buy another membrane.

The TDS meter I'm using is this one

http://www.tdsmeter.com/products/tdsez.html

This is the first one I've ever used. Ive used it on a few different water samples:

tap: 145
Water from RO unit: 26-27
Drain line from RO unit: 236
water from grocery store's ro unit: 1

I dont know, I guess I can see if my LFS will test the TDS for me, I really hope ur right and it turns out to be just the meter im using