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DewaynelovesAbby
Sat, 18th Oct 2008, 06:03 AM
I purchased a Home/Reef unit from AWI a couple weeks ago and am at my wits end on how to test the TDS. AWI assures me that the TDS will be at Zero on the DI side. However, I get the same basic reading on both the RO and the DI. I got a permeate pump and installed it last night and also replaced the Horizontal DI cartridge. But I still get 15 PPM on the RO and around 20 on the DI. I have a new tester that I am using. It is a HM Digital TDS-3. Any thoughts? Thanks.:at_wits_end:
Texreefer
Sat, 18th Oct 2008, 06:29 AM
A new cartride will test high for a good 20 minutes of use, you need to let a new system run for a bit before it flushes averything out.. also might find something known to have zero TDS and just double check your tester.
DewaynelovesAbby
Sat, 18th Oct 2008, 09:33 AM
Does it matter whether the pressure tank is on or off?
Is the fast flush supposed to be open or closed?
DewaynelovesAbby
Sat, 18th Oct 2008, 09:36 AM
Would distilled water have a Zero TDS?
DewaynelovesAbby
Sat, 18th Oct 2008, 09:39 AM
One other question; is it normal for the permeate pump to come on and off and the water to surge slightly while the water is running? I understand that the pump isn't really coming on and off, since it isn't powered. But you can hear it every few seconds then the water spurts. Thanks.
DewaynelovesAbby
Sat, 18th Oct 2008, 04:03 PM
I got some distilled water from the store and it reads zero with the tester. I let the DI run while we were gone this AM for over an hour and the tests still come to 14-15 on both the RO and DI. I wonder now if this means they sent me another bad DI cartdridge?
CoryDude
Sat, 18th Oct 2008, 10:13 PM
Could be a dumb question. Have you checked to make sure the DI cartridge isn't installed up-side-down? I know Russ at Buckeye had a similar situation as yours:

http://www.maast.org/forums/showthread.php?t=42730
Bill S
Sun, 19th Oct 2008, 10:31 PM
If you have a pressure tank, your TDS will never be zero. Ask Russ at Buckeye. The backpressure allows a bit of leakage. Same thing happens when the unit cycles on and off.
DewaynelovesAbby
Mon, 20th Oct 2008, 08:12 AM
Will you not get zero if you turn off the valve to the pressure tank?
Bill S
Mon, 20th Oct 2008, 09:23 AM
Yes, if you fill from the RO/DI unit with the pressure tank off, you will get zero. HOWEVER, it will take a bit of running to get there. There is always some bleedthru of the membrane when it is shut off. That's why they don't recommend running directly from an RO/DI unit to a tank float valve. It cycles the RO/DI unit too much. Not only that, but it encourages a flood...