Resurrecting an old RODI unit.

[Saintnovakai]

Hey team. A reefer friend had an old RODI setup that he tossed my way but he remembers nothing about it. He says I can just change the filters out and I should be fine. Thing is, I don't know if this is a 75 or 100 or whatever GPD unit. I've previously been buying store RO. I have a few quick questions if you don't mind.

I just want top off water. I use seawater for the tank. So I doubt I'll need a huge GPD

1. Heard about rejection rate being higher relative to GPD. So can I use a 75 gpd membrane regardless of what the unit might have come with?

2. I hear that 1 and .5 sediment and carbon filters are best at protecting the RO membrane. What's best in your opinion

What filters would you recommend? I think my tap water has chlorine and not chloramine but I'm not sure.

Unit is old and dirty but I'm guessing new filters will awaken the dead. Lol

Any help would be appreciated.

 

[Nano427]

My BRS rodi came with 5 micron carbon and sediment filters, not sure if the .5 or 1 is better or not but I’m happy with it

 

[Irishman]

The GPD all depends on your membrane size you get. I would replace all filters and membranes.
The order I did was sediment, 1 regular carbon (I believe) and 1 chloramine carbon then membrane. I would also get a dual TDS meter, one before the membrane, so you know when your filters are going out, and one after the DI stage.

 

[TheOne]

Did you open the RO housing to see if the membrane has any info on it? You will have to match a flow restrictor to the RO membrane for it to work properly. Without knowing either then I would just replace both.

 

[Redfoxtang]

Depending on how clean you incoming water is, by this I mean if you have soft water. You can run a 100gpd unit with a 75gpd flow restrictor as this will save you on waste water. But like I said this all depends on how clean your incoming water is and if you have chloramines.

 

[Saintnovakai]

Ok so following the advice I got it's a 100gpd membrane from Applied Membrane Inc. So can I do the 75 with higher rejection rate without the restrictor or can I find a 100gpd with just as high rejection. Will look while I listen out for you guys. Thanks so far.

 

[bblumberg]

Buy yourself a Dow Filmtec membrane with 99% rejection. This typically means 75 gpd or lower as the 100 gpd membranes are usually only 97 or 98% rejection.

Here is one example- search for "Dow FilmTec BS60-1812-75"
For some reason R2R breaks the direct amazon link but you can get these at lots of places.

I like the flow restrictors/membrane flush valve rather than the inline flow restrctors. Search for "AFWFilters Valve Flushing Flow Restrictor for 75 GPD RO systems with 1/4-inch Quick Connect Fittings, White"

I very much dislike the little flow restrictors that go into the line.

All in all, a straghtforward job that will save you money in the long run compared with buying RO

 

[Irishman]

Ok so following the advice I got it's a 100gpd membrane from Applied Membrane Inc. So can I do the 75 with higher rejection rate without the restrictor or can I find a 100gpd with just as high rejection. Will look while I listen out for you guys. Thanks so far.

you’re going to need a flow restrictor no matter what, otherwise your membrane won’t work correctly and you’ll have an abnormally higher rejection rate. The flow restrictor forces the water to go through the membrane so you have a better clean to waste water ratio.