Question on TDS

[Corant1171]

HI, I have an aquatic life 100 gallon per day RO/DI machine. And I purchased a TDS meter from my LFS. I have flushed the unit before use and collected 5 gallons for my water change.
TDS readings:
Tap water: 432 TDS
Post RO/DI membrane: 11 TDS
I have read that anything above 0-1 TDS is unacceptable. I still have the option to return the machine until the end of the month. So should I return the unit and buy a more known unit, or should I try and fine an add-on for the aquatic life unit?
AQUATIC LIFE:

 

[Biglew11]

You might want to send it back and try one of these. From bulk reef supply.

https://www.bulkreefsupply.com/bulk-reverse-osmosis-filters-systems/reverse-osmosis-systems.html

From amazon

NEW YORK CITY ONLY - Due to high city water sediment, additional pre-filtration required before use.

432 tds coming in is getting pretty high. My tap water coming in is around 135 at the tap, so I cant say exactly how much filtration you need, maybe someone with higher tds tap water can tell you more.
with the aqueon filter they force you into using there proprietary filters. With a standard ro/di unit you can use any standard filters you want. You can also easily add on housings for more filtration. I started out with this.

https://www.f3images.com/IMD/1000/YSP1317/SpectraPure-Maxpure-90-GPD-RO-DI-System-99.jpg

After upgrades it's now a 7 stage. 200 gpd

 

[Randy Holmes-Farley]

Maybe the DI is depleted, or it is hooked up wring. A DI alone should get to 0-1 ppm TDS, it just gets depleted very fast alone.

 

[mfinn]

At what point are you getting the 11 TDS reading? After the ro membrane? After the di resin?
Neither point would be a good place to have that much TDS.
It's not easy to tell how big the containers are, but with tap water with a TDS of 432, I would want a top of the line ro/di unit.

Also, if you are collecting water coming from the end point ( after di resin ) and letting it sit in a container that has had saltwater in it at any point, you may be getting a bad reading.
I know any containers I've used to hold salt water in, I can never seem to get clean enough to put rodi water in and get a 0 TDS reading.

 

[Corant1171]

At what point are you getting the 11 TDS reading? After the ro membrane? After the di resin?
Neither point would be a good place to have that much TDS.
It's not easy to tell how big the containers are, but with tap water with a TDS of 432, I would want a top of the line ro/di unit.

Also, if you are collecting water coming from the end point ( after di resin ) and letting it sit in a container that has had saltwater in it at any point, you may be getting a bad reading.
I know any containers I've used to hold salt water in, I can never seem to get clean enough to put rodi water in and get a 0 TDS reading.

I am getting 11 TDS from my top off bucket, I put my RO/DI water in there to top off and it has only held freshwater. It is just a run of the mill 5-gallon plastic jug. So from your post I decided to hook up the machine again and run water straight from the output into a glass container and take the TDS. To my astonishment it is reading 0 TDS!! So now I know that my RO/DI unit is not the actual issue here it is the storage method I am using. So my new question is what do you use to hold your top off water and what do you use to mix your saltwater in when you do a water change?

 

[mfinn]

I am getting 11 TDS from my top off bucket, I put my RO/DI water in there to top off and it has only held freshwater. It is just a run of the mill 5-gallon plastic jug. So from your post I decided to hook up the machine again and run water straight from the output into a glass container and take the TDS. To my astonishment it is reading 0 TDS!! So now I know that my RO/DI unit is not the actual issue here it is the storage method I am using. So my new question is what do you use to hold your top off water and what do you use to mix your saltwater in when you do a water change?

Yeah, I had the same issue a few years back.
I had a batch of fresh rodi water in a barrel and for some reason decided to test it with a hand held tds meter and it came back with much higher tds.
I had at one time used the barrel to mix up a batch of saltwater, but had very carefully cleaned it out before using it again to store rodi water.
So I went around my garage and cleaned out a couple buckets I had. I used vinegar and flushed and wiped and flushed several times. Then add a few gallons of 0 TDS rodi water, using the TDS meter on the unit and the hand held one to confirm it was 0 TDS.
I let the water sit in the buckets for a few minutes and sure enough I was showing TDS in those buckets.
So it seems to me that pretty much and plastic bucket is going to add TDS to rosi water if it's been used to mix saltwater.

Now I use a dedicated barrel just for mixing saltwater and a new 55 gallon barrel for just rodi water.

 

[Randy Holmes-Farley]

I am getting 11 TDS from my top off bucket, I put my RO/DI water in there to top off and it has only held freshwater. It is just a run of the mill 5-gallon plastic jug. So from your post I decided to hook up the machine again and run water straight from the output into a glass container and take the TDS. To my astonishment it is reading 0 TDS!! So now I know that my RO/DI unit is not the actual issue here it is the storage method I am using. So my new question is what do you use to hold your top off water and what do you use to mix your saltwater in when you do a water change?

It doesn't take much salty dust to land in a reservoir to boost the TDS a bit. I wouldn't worry about it.
TDS itself is not a concern if you use a decent container, not matter what it seems to read later.

 

[Camaro Show Corals]

It doesn't take much salty dust to land in a reservoir to boost the TDS a bit. I wouldn't worry about it.
TDS itself is not a concern if you use a decent container, not matter what it seems to read later.

So do you not recommend using 5 gallon buckets for containers?

 

[Randy Holmes-Farley]

So do you not recommend using 5 gallon buckets for containers?

Most plastic buckets will be fine. My point was that a little TDS showing up is common from dusts, residual contaminants, etc. It's not typically a sign of unacceptable water.