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Are you getting 0 TDS from your RO machine?


Dennerle
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Anyone getting absolute 0 TDS from your RO machine?

 

I'm using 5 stage and get 7 to 9 TDS.

 

Please share your stages and TDS

 

 

 

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Equipment

• 60cm x 45cm x 50cm tank

• Chiller at 25 to 26 Celsius

• OASE Biomaster 250

• 75W lighting

• Jebao SOW-5M Wavemaker

• RODI water with 25% weekly water change

• no protein skimmer/ no calcium reactor

Livestock

▪︎2 Ocellaris Clown

▪︎1 White Bellied Yellow Wrasse

▪︎1 Yellow Tang

▪︎2 Green-Blue Chromis

▪︎1 Orange Spotted Goby

▪︎1 Tailspot Blenny

▪︎1 Tiger Pistol Shrimp

 

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You said 'RO' does that mean you dont have DI resin?? I get 0 TDS all the time from a simple 5 micron sediment filter, two carbon blocks, a basic 75gpd RO membrane and some mixed bed DI resin.

I tend to work backwards when I have an RODI issue (The sediment and carbon filter tend to help the RO membrane last longer. The membrane does all the heavy lifting, hence the reason to work backwards). So, firstly check your DI resin is fully packed well into the DI canister, as you could be reading some creep if not. If all packed in, does it need replacing?? If not and the resin is ok, next bet is your RO membrane. All membranes have a rejection rate. So if rejection rate of 99% then with Singapore water at around 60-70tdi you shouldn't be getting much above 1 or max 2tdi (as TDI machines are not super accurate), hence, assuming your resin is all good a TDS reading of 7 would indicate the need to replace your RO filter.

Hope that helps.

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You said 'RO' does that mean you dont have DI resin?? I get 0 TDS all the time from a simple 5 micron sediment filter, two carbon blocks, a basic 75gpd RO membrane and some mixed bed DI resin.

I tend to work backwards when I have an RODI issue (The sediment and carbon filter tend to help the RO membrane last longer. The membrane does all the heavy lifting, hence the reason to work backwards). So, firstly check your DI resin is fully packed well into the DI canister, as you could be reading some creep if not. If all packed in, does it need replacing?? If not and the resin is ok, next bet is your RO membrane. All membranes have a rejection rate. So if rejection rate of 99% then with Singapore water at around 60-70tdi you shouldn't be getting much above 1 or max 2tdi (as TDI machines are not super accurate), hence, assuming your resin is all good a TDS reading of 7 would indicate the need to replace your RO filter.

Hope that helps.

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I'm using a RODI component in this manner: 5 micro -> carbon -> 10 micron -> 75g membrane -> DI

Maybe I should replace with 2 carbon instead?

My DI should be well packed in. Mine supposed to be 4 stage but I add on another tumbler with DI to make it 5 stage.

Btw I an using a RODI meant for drinking water but that should work too instead of using a aquarium aquarium RODI?




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Equipment

• 60cm x 45cm x 50cm tank

• Chiller at 25 to 26 Celsius

• OASE Biomaster 250

• 75W lighting

• Jebao SOW-5M Wavemaker

• RODI water with 25% weekly water change

• no protein skimmer/ no calcium reactor

Livestock

▪︎2 Ocellaris Clown

▪︎1 White Bellied Yellow Wrasse

▪︎1 Yellow Tang

▪︎2 Green-Blue Chromis

▪︎1 Orange Spotted Goby

▪︎1 Tailspot Blenny

▪︎1 Tiger Pistol Shrimp

 

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  • SRC Member

There is much you could try, from simply reordering you pre stage, through to removing the last RO membrane. However in the longterm I certainly would consider moving to the 5--> carbon-->carbon inital stage setup simply because it is tried and tested.

I suspect it is the RO membrane. I had a similar spike once, with a double RO set up just like yours and it turned out my RO membranes were depleted. Because I only had one spare, I moved to a single new RO membrane and instantly got 0TDS.

Drinking water system... hmmm. I doubt would be an issues as the hardware typically is the same (10inch enclosed filters) so unless you are using some strange taste adjusting filters or MWF filters which have different chemicals inside of them you should be fine.

Good luck.





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Those used for drinking is not the same as the aquarium one because human can’t drink 0 TDS rodi water. Those for drinking include some nutrients required by our body.


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But my 5 stages components does not have anything that enhances taste...hmmm

Those used for drinking is not the same as the aquarium one because human can’t drink 0 TDS rodi water. Those for drinking include some nutrients required by our body.


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Equipment

• 60cm x 45cm x 50cm tank

• Chiller at 25 to 26 Celsius

• OASE Biomaster 250

• 75W lighting

• Jebao SOW-5M Wavemaker

• RODI water with 25% weekly water change

• no protein skimmer/ no calcium reactor

Livestock

▪︎2 Ocellaris Clown

▪︎1 White Bellied Yellow Wrasse

▪︎1 Yellow Tang

▪︎2 Green-Blue Chromis

▪︎1 Orange Spotted Goby

▪︎1 Tailspot Blenny

▪︎1 Tiger Pistol Shrimp

 

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An RO membrane is considered the most important element of an RODI system. The sediment and carbon filters act as pre filters to reduce the amount of large moleculed contaminants entering and clogging the membrane. It is the membrane that does all the heavy lifting. Why the RO is so important is unlike the carbon blocks it works under pressure (hence good systems include a pump) and as such it literally strains virtually all unwanted impurities from the mains supply, allowing only 'pure' water molecules to pass through... so as long as you are happy having small molecule impurities, salts, heavy metals, chemicals, pesticides, and microbial contaminants (including viruses and bacteria) in your tank then you don't need an RO membrane ;)

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  • 9 months later...
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Hi, borrowing this thread to ask a related question on RODI. I have been having this RODI unit for about 1 - 1.5 years. I perform weekly water change of 14L. All the bars on the indicator show 5 bars, but I feel the TDS is slowly creeping up recently. I never reached 0 TDS. Normally just 2- 3. These days, it is around 3-4. I checked with LFS, and they advised to change based on the bar reading. Since it is still showing 5 bars, there is no need to replace it. Seeking some advice from the folks here. Thanks in advanceIMG-20200718-WA0038.jpg

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