The Basics of an RODI Filter

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I'm looking to get an RO system. The things I'm most concerned about are 1) getting the right system, and 2) getting it installed correctly. It seems as if most people here install them themselves, but I'm not confident me and the hubby can do it without messing it up. Who would be the best person to install one? A plumber? A water purification company like Culligan? Any recommendations on the best systems, i.e. best filtration with least waste? TYIA!

I would go with a BRS filter or spectrapure. As far as setting one up it’s pretty basic.


 
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A lot of filters are mostly put together for really so it’s just a question of connecting a garden hose style fitting to a water facet.

You can see the lines are labeled

9DE240C7-4653-4781-9597-18CFAC06358A.jpeg

The fitting unless you want to tee off under the sink would look like this. ABC8A36C-F02B-4471-BC9C-FAEFAAF8F080.jpeg
You can see everything is pretty much put together for you. 1E5D64EE-B3D9-4409-A625-0871403A3AA7.jpeg B9523155-1E55-4283-8F1B-1473FB3D6639.jpeg
 
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MamaP

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I would go with a BRS filter or spectrapure. As far as setting one up it’s pretty basic.



Thank you!
 

Thomas Wieczorek

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Hey just my 2 cents on some people getting a hight tds...one time i went and changed my filters and when i went to put then back together I forgot one of the rubber seals (gasket) and I was getting a high tds and couldn't figure out why cause I had just put new filters. Well I seen the gasket and installed it. Screwed everything back tight and bam. 0 tds....also I purchased a "high flow" r.o membrane once that was giving me 33 tds before resin, but the ro I replaced was giving me 11 tds before resin....so watch those 2 things
 

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does anyone have a general idea of what the pressure should be after the 3rd stage (2nd carbon filter)? My initial pressure from the tap is 62psi with 70 degree water
 

Randy Holmes-Farley

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One thing not mentioned that confuses folks is that if you are using separate anion and cation resins (meaning you have two separate cartridges instead of one mixed bed cartridge), the TDS after the first of those two in line will be (must be) higher than the TDS coming into that cartridge.

It is not an indication that anything is wrong with that resin, it is just the way they work. The H+ or OH- that they swap into the water in place of the ions in the water are much more conductive than any other ions, so TDS rises. After (in, really) the second DI, the OH- and H+ combine to form nonconductive water and the TDS drops to 0.
 

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I would like to see an article that addresses the "whats the best RODI unit" question.
Unless its a sealed cartridge systems that locks a user into a manufactures parts, a lot of them use the same outsides and inside filters, brackets ect... Why would one be better than another when they are all interchangable. You can have a 4 stage and easily add cartridges to make it a 7 stage. You can swap out a 100 GPD membrane with 150 gpd membrane and change the restrictor if you need more water, just like you can add a booster pump to any unit. Anyone game ?

Note: I did find some weird threaded canister on ebay that was not std and therefore not canister/housing interchangeable with other units.
 
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One thing not mentioned that confuses folks is that if you are using separate anion and cation resins (meaning you have two separate cartridges instead of one mixed bed cartridge), the TDS after the first of those two in line will be (must be) higher than the TDS coming into that cartridge.

It is not an indication that anything is wrong with that resin, it is just the way they work. The H+ or OH- that they swap into the water in place of the ions in the water are much more conductive than any other ions, so TDS rises. After (in, really) the second DI, the OH- and H+ combine to form nonconductive water and the TDS drops to 0.

Didn’t know that but makes since.

Thanks
 
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Just as a small add on you can add a T and 2 valves after the RO and before the DI to flush TDS creep out before it goes into the DI cartridge. This will make your DI last longer. TDS creep is high TDS water that you end up with from the water sitting in the RO when it’s not being used.
 

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Just as a small add on you can add a T and 2 valves after the RO and before the DI to flush TDS creep out before it goes into the DI cartridge. This will make your DI last longer. TDS creep is high TDS water that you end up with from the water sitting in the RO when it’s not being used.

John Guest makes a 3 way valve also

iu
 

illumnae

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If I have a locally assembled 200gpd rodi system with an auto shut off valve and I would like to upgrade it to a 400gpd system, is it simply a matter of changing the flow restrictor to a 400gpd unit (like this one Amazon product) and then replacing the membrane with a 400gpd membrane? Or do I need to do additional stuff to get the system upgraded?

I'm no longer able to get anything above 200gpd locally and I just got a new 600 gallon tank so I need to massively increase my water production capabilities. If anyone can teach me how to modify the system to run 2x 400gpd membranes in parallel for an 800gpd system that would be even better, but I have to admit I'm not so great at diy so that may be a stretch.

Thanks!
 
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Yes just change the membrane and flow restrictor. If your going to make that much water I would filter the waste as well. You want to get down to a 1:1 ratio. For a normal 3:1 RO you would be running 1200gals through the filter to get your 400gals of RO/DI water.
 
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As far as running two ROs parallel I’ve never done it but I would think you could just put a Tee before and after the two membranes. My concern would be having the right pressure going through them. To much or to little and the membranes will go bad quickly.
 

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Yes just change the membrane and flow restrictor. If your going to make that much water I would filter the waste as well. You want to get down to a 1:1 ratio. For a normal 3:1 RO you would be running 1200gals through the filter to get your 400gals of RO/DI water.

As far as running two ROs parallel I’ve never done it but I would think you could just put a Tee before and after the two membranes. My concern would be having the right pressure going through them. To much or to little and the membranes will go bad quickly.

Thank you! How would I filter the waste to get it to 1:1? Run the waste through another membrane and connect both outputs together?
 
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Thank you! How would I filter the waste to get it to 1:1? Run the waste through another membrane and connect both outputs together?



 

illumnae

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Thanks so much! This is pretty awesome... so I get double the GPD and reduce the waste ratio in 1 single fix!
 
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Thanks so much! This is pretty awesome... so I get double the GPD and reduce the waste ratio in 1 single fix!

Yep. Do you have a build thread for that tank? At one point I would like to set up a 300+ gallon tank in my basement.
 

illumnae

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Yep. Do you have a build thread for that tank? At one point I would like to set up a 300+ gallon tank in my basement.
Sorry it's a freshwater tank so no build thread here. I'm using an rodi as I'm keeping wildcaught south american fish that require low ph/low tds water. I've attached a picture of the tank slowly filling using my current 200gpd system - that picture was taken 24h after starting the fill.

I think it's quite cool that I'll still be using a 200gpd flow restrictor while getting 400gpd output. If i need a booster pump due to the increased pressure from the 2nd membrane (currently don't need one with the single membrane), it should be installed after the last carbon prefilter and before the first membrane right?

Would it work with a 3rd membrane in series to obtain 600gpd? I assume I'll need multiple booster pumps to achieve that?
 

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