2 membranes ro-di

[Beam]

I finally solved my problem by adding a carbon cartridge and tripling the amount of di resin,
it was the simplest method, and it does the trick.

 

[RoninNV]

That's what I was thinking but I guess with water coming out high out of the membrane the RO gets used up quickly?

I have a pump that will flush the membrane automatically, so the membrane is still in great shape because of that pump. I've been running the same membrane for a year and still coming out between 6 to 15. The DI then takes care of the rest.

 

[t5Nitro]

Since this is somewhat relevant and to not start a new thread -- any ideas on running two 75 gpd membranes (water saver kit) with ro smart buddy booster pump versus running a single 150 gpd, or even 100 gpd membrane with ro buddy booster pump? Debating taking down my water saver kit and going back to single membrane but not sure the best option.

Seems like consensus is not to run these dual membrane systems. The ro buddy has a built in 300 flow restrictor. Any ideas which single membrane would work with it with tap tds of 200?

 

[Opus]

Since this is somewhat relevant and to not start a new thread -- any ideas on running two 75 gpd membranes (water saver kit) with ro smart buddy booster pump versus running a single 150 gpd, or even 100 gpd membrane with ro buddy booster pump? Debating taking down my water saver kit and going back to single membrane but not sure the best option.

Seems like consensus is not to run these dual membrane systems. The ro buddy has a built in 300 flow restrictor. Any ideas which single membrane would work with it with tap tds of 200?

Depends on if you want to spend extra for a 99% rejection membrane. I run a spectrapure 99% rejection rated membrane and I get tds of 3 to 4 after the membrane and my tap is usually over 400. A stock membrane should get you around 97 to 99% rejection rate. Whatever you get, just make sure you get a matching flow restrictor.

 

[BZOFIQ]

I have a pump that will flush the membrane automatically, so the membrane is still in great shape because of that pump. I've been running the same membrane for a year and still coming out between 6 to 15. The DI then takes care of the rest.

Me too, but I get 0 out of the membranes

 

[t5Nitro]

Depends on if you want to spend extra for a 99% rejection membrane. I run a spectrapure 99% rejection rated membrane and I get tds of 3 to 4 after the membrane and my tap is usually over 400. A stock membrane should get you around 97 to 99% rejection rate. Whatever you get, just make sure you get a matching flow restrictor.

I don't know this answered the question unless I'm not understanding what you're writing. Was wondering whether two 75 gpd membranes in series is a better option than a single 150 gpd membrane on its own. In the past, I had upgraded the 75 to a 150 by adding a water saver kit, although I'm not entirely sure I need two membranes. Maybe it's better to have a single membrane rated at higher gpd than two smaller membranes? The second membrane usually gets hit with TDS water higher than the source water given that its fed by waste water from membrane 1, right?

Or is this because the lower gpd membranes tend to have a higher rejection rate so it's easier on your DI stage following? In this sense, would it still be worth taking down the water saver kit, changing the dual 75 membranes to a single high rejection 90 or 100 gpd membrane?

Wondering which direction you'd go with this. I'm kind of wondering what the point of the water saver kits are after thinking about this more.

 

[Opus]

I have a pump that will flush the membrane automatically, so the membrane is still in great shape because of that pump. I've been running the same membrane for a year and still coming out between 6 to 15. The DI then takes care of the rest.

Flushing the membrane really doesn't do much. My membrane is 3 or 4 years old and I'm getting 4 after the membrane and that is with 400 tap tds.

 

[Opus]

I don't know this answered the question unless I'm not understanding what you're writing. Was wondering whether two 75 gpd membranes in series is a better option than a single 150 gpd membrane on its own. In the past, I had upgraded the 75 to a 150 by adding a water saver kit, although I'm not entirely sure I need two membranes. Maybe it's better to have a single membrane rated at higher gpd than two smaller membranes? The second membrane usually gets hit with TDS water higher than the source water given that its fed by waste water from membrane 1, right?

Or is this because the lower gpd membranes tend to have a higher rejection rate so it's easier on your DI stage following? In this sense, would it still be worth taking down the water saver kit, changing the dual 75 membranes to a single high rejection 90 or 100 gpd membrane?

Wondering which direction you'd go with this. I'm kind of wondering what the point of the water saver kits are after thinking about this more.

If you are wanting to stay at 150, I would go with just the one membrane. The membrane from BRS says it has a 98% rejection so you should get a tds of 4 after the membrane with your 200tds tap. As you stated, with your dual 75 you are sending even more polluted water to the second membrane which will shorten its live over the 1st membrane. If saving water is your main concern, then stick with your current setup or invest in one that does 1:1 rejection.

 

[BZOFIQ]

Flushing the membrane really doesn't do much. My membrane is 3 or 4 years old and I'm getting 4 after the membrane and that is with 400 tap tds.

It does, I flush before and after production and have very low TDS creep in the RO tank. Initially produced water is higher in TDS if you dont flush and so you burn your DI resin quicker. I use my system for drinking water as well so the filter is engaged and pressure tank is filled sometimes multiple times per day.

If you have a dual (or triple) TDS probes you can easily see the TDS right after you engage the filter and after few minutes of production. Take a look or at least google TDS Creep.

Reef Addicts - RO/DI TDS Creep - is it worthy of concern?

When water sits in the membrane housing for a duration, TDS rises as it wicks out of the membrane. The initial 60 to 90 seconds when the system turns on will send this burst of TDS into the DI resin...

www.reefaddicts.com

 

[RoninNV]

Flushing the membrane really doesn't do much. My membrane is 3 or 4 years old and I'm getting 4 after the membrane and that is with 400 tap tds.

Vegas has tap water that is over 550, a lot of times closer to 600, so flushing makes a huge difference. Like BZOFIQ mentioned, it eliminates TDS creep and DI last longer. I have 3 RO units in my house, 1 in the kitchen, 1 in my Bar and 1 for my aquariums. None will run 0 TDS due to the bad water quality here. That's why I use DI media in all of my RO units.

 

[Opus]

Vegas has tap water that is over 550, a lot of times closer to 600, so flushing makes a huge difference. Like BZOFIQ mentioned, it eliminates TDS creep and DI last longer. I have 3 RO units in my house, 1 in the kitchen, 1 in my Bar and 1 for my aquariums. None will run 0 TDS due to the bad water quality here. That's why I use DI media in all of my RO units.

Are you talking about flushing the membrane or initially by-passing the DI when you start up the unit, which is not flushing. I see flushing used all the time on here but they actually mean by-passing the DI.

 

[KStatefan]

Russ @Buckeye Hydro has a good post on this from a few years ago.

Let's Talk RO & RODI

I wanted to introduce, or re-introduce some common jargon pertaining to RO and RODI systems that few people in the hobby commonly use. PERMEATE - the water that has made its way through the RO membrane. Often called "RO water." In most situations, the TDS of permeate should be 5% or less of...

www.reef2reef.com

 

[BZOFIQ]

Are you talking about flushing the membrane or initially by-passing the DI when you start up the unit, which is not flushing. I see flushing used all the time on here but they actually mean by-passing the DI.

I do both...via couple of automated solenoids

 

[BZOFIQ]

Russ @Buckeye Hydro has a good post on this from a few years ago.

Let's Talk RO & RODI

I wanted to introduce, or re-introduce some common jargon pertaining to RO and RODI systems that few people in the hobby commonly use. PERMEATE - the water that has made its way through the RO membrane. Often called "RO water." In most situations, the TDS of permeate should be 5% or less of...

www.reef2reef.com

Very well explained - in simple terms. I've learned a lot/consulted with him when I built my custom filter.

 

[Opus]

I do both...via couple of automated solenoids

What are you trying to accomplish by flushing?

 

[Sisterlimonpot]

I have been running a dual membrane in series for years now. My DI has lasted a lot longer thanks to this configuration.

I've outlined it in a thread on another forum, the biggest change I made was that I removed the stock flow restrictors and replaced them with adjustable regulators.

Here's the thread:

Untraditional Dual Membrane System (RODI)

Throughout the years in this hobby I've accumulating a lot of knowledge that's not traditionally in my field of expertise and because of that I've always tried to associate concepts with what I know, just so that I can make sense of it and create a foundation on which to build upon. More times...

humble.fish

 

[t5Nitro]

If you are wanting to stay at 150, I would go with just the one membrane. The membrane from BRS says it has a 98% rejection so you should get a tds of 4 after the membrane with your 200tds tap. As you stated, with your dual 75 you are sending even more polluted water to the second membrane which will shorten its live over the 1st membrane. If saving water is your main concern, then stick with your current setup or invest in one that does 1:1 rejection.

Thanks for this! I have a question on the flow restrictor. If I can keep using the RO buddy it has a built in 300 flow restrictor. Should I add an additional flow restrictor at the membrane to get an added total of whatever number is recommended for the membrane size?

 

[Buckeye Hydro Verified Sponsor]

Those weeny prefilters on an RO Buddy really aren't a good match for a 150 gpd membrane.

 

[t5Nitro]

Those weeny prefilters on an RO Buddy really aren't a good match for a 150 gpd membrane.

What i mean is that would you still consider its flow restrictor and add a smaller in line one, like a 550 ml restrictor barrel for a total 850 ml restrictor? Or maybe they don't work that way.

 

[Cichlid Dad]

I run a smart buddie on a BRS 75 gallon per day 6 stage rodi unit. I have 75 tds coming in and 2 tds going to the di units. It takes 40 minutes to fill 5 gallon jug, 4 hrs to fill 30 gallon rubber maid. From what I understand they are only good for 100 gallon per day unit's.