RODI Not Putting Out 0 TDS

[Woodyman]

I installed a new membrane and the second DI resin chamber. The PSI is sitting around 85 and I'm still getting 36 TDS out of the membrane. I'm starting to think that the Dow membranes from BRS are just crap if it's like this

What's the membrane model #

 

[Woodyman]

What's the membrane model #

Some membranes take longer than others to 'break in'

How much have you flushed through the new filters so far?

 

[LeftyReefer]

Not sure if anybody already asked this already, but when you install the RO membranes, you are pushing it all the way in until you hear a click/pop, correct?

Almost seems like your RO membrane isn't seated correctly and is letting TDS by.... just a guess.... I didn't read the whole thread.
I'd make sure there isn't any debris or anything in your RO housing that might be preventing the membrane from being inserted all the way?

 

[Schraufabagel]

Not sure if anybody already asked this already, but when you install the RO membranes, you are pushing it all the way in until you hear a click/pop, correct?

Almost seems like your RO membrane isn't seated correctly and is letting TDS by.... just a guess.... I didn't read the whole thread.
I'd make sure there isn't any debris or anything in your RO housing that might be preventing the membrane from being inserted all the way?

I did push it until it popped and seated fully

 

[Schraufabagel]

What's the membrane model #

TW30-1812-100HR

I ran the system with the new membrane for about 20 minutes. Made about 2 gallons

 

[Woodyman]

TW30-1812-100HR

I ran the system with the new membrane for about 20 minutes. Made about 2 gallons

It's going to need longer. Especially on a dry shipped membrane.

 

[Schraufabagel]

It's going to need longer. Especially on a dry shipped membrane.

I'll bypass the DI canisters and run it for another hour or so straight to the drain

 

[Woodyman]

I'll bypass the DI canisters and run it for another hour or so straight to the drain

I like the 'wet tested' membranes for this reason. Less of a wait for the membrane to rehydrate and work at peak efficiency.

 

[Schraufabagel]

I like the 'wet tested' membranes for this reason. Less of a wait for the membrane to rehydrate and work at peak efficiency.

Is that what the Spectrapure ones are?

 

[LeftyReefer]

The DOW data sheet actually tells you to "rinse" new (dry) membranes for 24 hours prior to first use.

I'm not sure if "rinse" means to actually run water through them for 24 hours or if "rinse" just means let them sit in a bucket of clean rodi for 24 hours..... I've never flushed/run one for 24 hours, but I'm pretty sure my RODI unit's directions said to flush any new membranes for at least 2 hours and discard all water, so that is what I did when I installed my membrane for the first time. After 2 hours, mine was reading 1 TDS out of RO though, not 20.

I'm using the same membrane btw. TW30-1812-100HR.

 

[Schraufabagel]

The DOW data sheet actually tells you to "rinse" new (dry) membranes for 24 hours prior to first use.

I'm not sure if "rinse" means to actually run water through them for 24 hours or if "rinse" just means let them sit in a bucket of clean rodi for 24 hours..... I've never flushed/run one for 24 hours, but I'm pretty sure my RODI unit's directions said to flush any new membranes for at least 2 hours and discard all water, so that is what I did when I installed my membrane for the first time. After 2 hours, mine was reading 1 TDS out of RO though, not 20.

24 hours would be a lot of water... (100 gallons) so I'm guessing it means soak in RODI maybe?

 

[Woodyman]

Is that what the Spectrapure ones are?

Yes SpectraPure sells the wet tested.

 

[Woodyman]

24 hours would be a lot of water... (100 gallons) so I'm guessing it means soak in RODI maybe?

Yes a soak in RO/DI would help.

On your next dry membrane I would say open it up, place it submerged in a bucket of RO/DI and let sit 24-48 hours. Then install it in the system let it run for an hour or more and let it sit at least another 24 hours with pressure on the membrane.

 

[Woodyman]

The problem with dry membranes is you don't know how long they have been sitting. While they don't go bad, the fresher they are the quicker the 'break-in'

 

[Woodyman]

24 hours would be a lot of water... (100 gallons) so I'm guessing it means soak in RODI maybe?

Technically speaking they do mean 24 hours of run time. Not soaking. But a soak isn't going to hurt.

You just want the membrane to be fully hydrated and rinsed of any preservatives which is why they say 24 hours.

Typical RO systems don't run DI so those preservatives would be leached into drinking water without the purge.

Our DI resin should remove any leftover contamination after the RO so a full 24 hour purge isn't strictly necessary, you just want to ensure the membrane is fully saturated and hydrated.

 

[LeftyReefer]

@Woodyman Do you know what the difference is between the following (2) spectrapure membranes?
other than the obvious 90 gpd vs 100 gpd... lol

both are the same price, but lacking in info/details.

SpectraPure® SpectraSelect® Plus 99% Rejection RO Membrane 90GPD​

and the

SpectraPure® Eliminator® RO 100 GPD Replacement RO Membrane​

 

[Woodyman]

@Woodyman Do you know what the difference is between the following (2) spectrapure membranes?
other than the obvious 90 gpd vs 100 gpd... lol

both are the same price, but lacking in info/details.

SpectraPure® SpectraSelect® Plus 99% Rejection RO Membrane 90GPD​

and the

SpectraPure® Eliminator® RO 100 GPD Replacement RO Membrane​

Off hand I do not. I use the SpectraSelect in my system. They are both private label DOW membranes, let me see what specifics I can get outside of the 10GPD difference. I'm guessing not much else, but I'd like to verify first.

 

[Woodyman]

Off hand I do not. I use the SpectraSelect in my system. They are both private label DOW membranes, let me see what specifics I can get outside of the 10GPD difference. I'm guessing not much else, but I'd like to verify first.

Both the SpectraSelect and Eliminator are wet tested, but I don't know that the Eliminator are speced out to the 99%

 

[KStatefan]

@Woodyman Do you know what the difference is between the following (2) spectrapure membranes?
other than the obvious 90 gpd vs 100 gpd... lol

both are the same price, but lacking in info/details.

SpectraPure® SpectraSelect® Plus 99% Rejection RO Membrane 90GPD​

and the

SpectraPure® Eliminator® RO 100 GPD Replacement RO Membrane​

The eliminator 100 is just a standard 100 gpd membrane while the Select is a binned membrane to get the higher rejection rate.

 

[Woodyman]

The eliminator 100 is just a standard 100 gpd membrane while the Select is a binned membrane to get the higher rejection rate.

"The Eliminator membrane is a non-tested membrane and still TFC with a minimum rejection of 96% while the SpectraSelect membrane is a hand tested RO membrane in which will provide minimum 98% rejection which will result in longer-lived DI filters"

That's a response from the Spectrapure rep I deal with. So outside of the 10GPD it's just the fact that one is hand tested and the other is not.