RODI Unit takes over an hour to flush

[zwieseldave]

Hi,

Ive had my RODI unit for a few years and usually after 10-15 mins it drops to 0 in Flush mode, but I have a new set of filters on and its taking over an hour to drop to 0, any ideas whats going wrong???

 

[ying yang]

Can only think to say check that all housings / filters in right way around and in properley and di resin packed in tight and check all valves open right and through process of elimination ( removing sone tubing) see if a valve not failed )
Other than that ummmm.
Woodyman has a good right up o rodi units that he did the other month ,maybe some helpful tips in there

 

[ying yang]

RO/DI Basic Guide

There are always a lot of questions regarding which RO/DI setup do I need, how many stages, how do I know when to change filters/membranes, I’m getting a weird TDS value, etc. Hopefully this clarifies a few things and helps some of you out one day. My first recommendation would be to find the...

www.reef2reef.com

Here is his thread on rodi,maybe something in there,not read in a bit so unsure and about to take little one to museum so no time to read through and check sorry.
@Woodyman can assist when comes.
And ask questions like did you rinse out the carbon block so no fines still lingering about and stuff like this ^_^
Good luck

 

[Woodyman]

Can only think to say check that all housings / filters in right way around and in properley and di resin packed in tight and check all valves open right and through process of elimination ( removing sone tubing) see if a valve not failed )
Other than that ummmm.
Woodyman has a good right up o rodi units that he did the other month ,maybe some helpful tips in there

As stated by @ying yang check that everything was reinstalled correctly.

If you only swapped out filters and didn't mess with anything else, then there are two possibilities that come to mind off the top of my head, either something is installed wrong, or in the process of changing you had something dislodge and become stuck in a tube that is restricting flow.

What all did you do the unit?
What filters got changed?
Did you purge filters (carbon) prior to sending water through your RO membrane?

 

[ying yang]

Wow your up early woodsman.i thought be few hours yet ha ha.
As even east coast America is 5 hours behind me in England.
Ummm just googled it and ohio 4 hours behind so maybe because we haven't changed our clocks yet for summertime and you did yours couple weeks ago.
Anyhow great your trying help someone so early,very kind ^_^

 

[Woodyman]

Wow your up early woodsman.i thought be few hours yet ha ha.
As even east coast America is 5 hours behind me in England.
Ummm just googled it and ohio 4 hours behind so maybe because we haven't changed our clocks yet for summertime and you did yours couple weeks ago.
Anyhow great your trying help someone so early,very kind ^_^

Only a few hours, I've got family over there so I'm familiar with the time change!

Just a tad later then a normal M-F for me.

 

[LeftyReefer]

How does it drop to 0 TDS in flush mode? Unless I'm not understanding what flush mode is....

In flush mode, it isn't actually pushing water through the RO membrane, nor are you sending it through the DI, so why would it ever drop to 0 TDS while flushing?

I flush my membrane until TDS drops down to 3 or 2 TDS, then I turn off the flush valve, and close by DI bypass valve, sending water through the RO and DI stage, then you get 0 TDS water.

 

[Woodyman]

How does it drop to 0 TDS in flush mode? Unless I'm not understanding what flush mode is....

In flush mode, it isn't actually pushing water through the RO membrane, nor are you sending it through the DI, so why would it ever drop to 0 TDS while flushing?

I flush my membrane until TDS drops down to 3 or 2 TDS, then I turn off the flush valve, and close by DI bypass valve, sending water through the RO and DI stage, then you get 0 TDS water.

Hopefully they come back with some answers...

 

[MERKEY]

Not sure if this helps but the 4th ro stage or...the little white one that lays on top of the other 3 ro the takes up to 4 hours to purge when replacing.

I was told this by BRS when I purchased my replacement.

You need to unhook your DI line and let it run through for about 4 hours.

If you did not replace that particular unit and if I am way off base here please disregard my comment.

 

[Woodyman]

Not sure if this helps but the 4th ro stage or...the little white one that lays on top of the other 3 ro the takes up to 4 hours to purge when replacing.

I was told this by BRS when I purchased my replacement.

You need to unhook your DI line and let it run through for about 4 hours.

If you did not replace that particular unit and if I am way off base here please disregard my comment.

4 hours may be to much or not enough, but a good safety number from BRS's stand point.

If you buy wet tested/pre-flushed you can basically start using immediately as long as they have been kept wet and hydrated. Still doesn't hurt to flush it for an hour or so after install.

The dry membranes can take anywhere from 1-24 hours to fully saturate and rehydrate.

 

[Gtinnel]

Not sure if this helps but the 4th ro stage or...the little white one that lays on top of the other 3 ro the takes up to 4 hours to purge when replacing.

I was told this by BRS when I purchased my replacement.

You need to unhook your DI line and let it run through for about 4 hours.

If you did not replace that particular unit and if I am way off base here please disregard my comment.

Wow I have never heard to flush a new membrane for that long. I’ve always heard close to an hour. I just checked buckeye hydro’s website and they say the manufacturer recommends 40 minutes.

 

[MERKEY]

Wow I have never heard to flush a new membrane for that long. I’ve always heard close to an hour. I just checked buckeye hydro’s website and they say the manufacturer recommends 40 minutes.

When I heard it I was thinning it was a bit long but after hearing this

4 hours may be to much or not enough, but a good safety number from BRS's stand point.

If you buy wet tested/pre-flushed you can basically start using immediately as long as they have been kept wet and hydrated. Still doesn't hurt to flush it for an hour or so after install.

The dry membranes can take anywhere from 1-24 hours to fully saturate and rehydrate.

I understand dry would take a while depending on which manufacturer you were using. Using preflushed saves a lot of time.

 

[Woodyman]

When I heard it I was thinning it was a bit long but after hearing this

I understand dry would take a while depending on which manufacturer you were using. Using preflushed saves a lot of time.

I use the pre tested/flushed from spectrapure, when I swap I put in the new one and give it about 10-30 minutes just because.

 

[MERKEY]

I use the pre tested/flushed from spectrapure, when I swap I put in the new one and give it about 10-30 minutes just because.

A few buddies use spectra and won't go back.

 

[Woodyman]

When I heard it I was thinning it was a bit long but after hearing this

I understand dry would take a while depending on which manufacturer you were using. Using preflushed saves a lot of time.

Most quality 'dry' membranes in the 90/100 gpd size shouldn't take much longer than an hour.

A bigger reason to flush longer most times is to ensure you remove any preservatives that may have been added to the membrane.

 

[Woodyman]

A few buddies use spectra and won't go back.

I won't go back. They are just private label/rebranded DOW membranes, but spectrapure does the flushing and testing to ensure they meet spec. (Occasionally membranes will fail, nothing is 100% in manufacturing) I don't mind paying the extra for a pre-hydrated and speced membrane.

 

[Woodyman]

This is the one I use.

SpectraPure® SpectraSelect Plus 99% Rejection RO Membrane

SpectraPure' SpectraSelect' Plus™ 99% Rejection Membranes set the industry standards for contaminate removal, high flow rate, and membrane longevity!

spectrapure.com

 

[Gtinnel]

Haha even on the BRS website for the FilmTec membrane it says to flush for an hour. It seems to me the person who said 4 hours either didn’t know what they were talking about, or was greatly erring on the side of caution.

I use the Dow FilmTec membranes because I’m cheap. All of the ones I’ve ever gotten give me 99% rejection, but maybe I’ve just been lucky so far.

 

[Woodyman]

Haha even on the BRS website for the FilmTec membrane it says to flush for an hour. It seems to me the person who said 4 hours either didn’t know what they were talking about, or was greatly erring on the side of caution.

I use the Dow FilmTec membranes because I’m cheap. All of the ones I’ve ever gotten give me 99% rejection, but maybe I’ve just been lucky so far.

The error margin on the DOW I'm sure is pretty low. You have a higher chance of it getting damaged in transit/handling I bet!