TDS readings question

[04mach1]

After running about 3 hours readings still arent 0. Going in its 84 after its 7. Its a brand new unit. Anyone have any suggestions? Is 7 o.k to use? The water I usally buy is reading 0.

[JJ70]

Does your unit have DI? If not then you may get a reading. It depends on the quality of membrane. 7 seems a little high with 84 in if the rejection rate is 98-99%. What is your pressure in?

[04mach1]

Not sure of the pressure.I have it running in my laundry room.
Yes it does have DI.

[JJ70]

That's strange then. The DI should take you to 0. Can you measure the TDS after the membrane to get an idea of your rejection rate?

[jdieck]

Also check the TDS of your tap water.

[04mach1]

<a href=showthread.php?s=&postid=7842123#post7842123 target=_blank>Originally posted</a> by jdieck
Also check the TDS of your tap water.
Already did it was 84.

[jdieck]

Sorry I missed it in the first post.

At 84 going in you shall have around 6 to 8 ppm at the membrane output for a 100 gpd membrane and 2 to 3 ppm at the ouput if your membrane is for 75 gpd or less. Out of the DI you shall be reading 0.
Just in case insure that the conections are properly done specially if you have an ASOV (Auto shut off valve) and that the water from the membrane is actually passing trough the DI filter and that the internal cartridge is properly seated in the housing.
Also insure that you are connecting the product line from the membrane to the DI, it is common to make the mistake of connecting the waste to the DI instead.

The connection goes like this. Inlet to sediment, sediment to carbon, carbon to ASOV "IN", ASOV "OUT" to membrane in, membrane product out to the ASOV (either of the unmarked ones), from remaining unmarked connection of the ASOV to the DI (Again do not confuse the membrane product out with the waste out of the membrane check your diagram) from DI to outlet valve.

[04mach1]

<a href=showthread.php?s=&postid=7842207#post7842207 target=_blank>Originally posted</a> by jdieck
Sorry I missed it in the first post.

At 84 going in you shall have around 6 to 8 ppm at the membrane output for a 100 gpd membrane and 2 to 3 ppm at the ouput if your membrane is for 75 gpd or less. Out of the DI you shall be reading 0.
Just in case insure that the conections are properly done specially if you have an ASOV (Auto shut off valve) and that the water from the membrane is actually passing trough the DI filter and that the internal cartridge is properly seated in the housing.
Also insure that you are connecting the product line from the membrane to the DI, it is common to make the mistake of connecting the waste to the DI instead.

The connection goes like this. Inlet to sediment, sediment to carbon, carbon to ASOV "IN", ASOV "OUT" to membrane in, membrane product out to the ASOV (either of the unmarked ones), from remaining unmarked connection of the ASOV to the DI (Again do not confuse the membrane product out with the waste out of the membrane check your diagram) from DI to outlet valve.
Thanks Ill check that in the a.m.

[AZDesertRat]

Time and time again I have tried to tell people here that trying to save money on RO/DI is not the answer. Yours is yet another case of a poor quality drinking water system being passed of as a reef quality RO/DI. I would almost bet with the filters and configuration that unit has you wil never see a TDS of 0 even with only 84 coming in to it. I would return it for a refund and spend another $50 to $75 and get something that is guaranteed to work and will come with excellent customer service and technical support. A couple of vendors heer build and sell only high quality units and stand behind their products. www.spectrapure.com has expressed interest in participating in group buys with reef clubs and groups here on RC. You can visit their sponsors forum for contact information. www.purelyh20.com is also a sponsor here and will build just about any configuration you want, but neither will sell you a system that won't do the job for you as your satisfaction is number one.

[rmills]

mach1, I have city water it reads close to 500 some times and after the RO/DO its around 2-3. Its made by coralife and cost about 230.00.
I still havent got a 0 rating but its alot better than before.
I would check your TDS meter.

[Jasen Hicks]

If its brand new, how long has it been running? Is your TDS meter inline? Is it a handheld? Make sure if its handheld you tap the end a bit under the waterline to ensure no airbubbles are in it, they will cause an erroneous reading. If its an inline version that checks in and out, then it could have a small bubble in it as well doign the same thing. I have seen this happen a lot on our water sampling equipment on our boat if the chemists dont sample the correct way.