RODI question.

[Ziggy17]

I currently have a 4 stage system with sediment, carbon, membrane, mixed bed DI. I’m thinking about adding a second 3 stage. I’d like to get another mixed bed and a silicate bed into the mix.

It’s my understanding that a second membrane stage will significantly reduce waste water and best optimize water use.
Is this correct?

If that’s correct;
And I use another 3 stage with a second membrane do I need a pump in between the first unit and the second unit to maintain the 60 ish PSI? My guess is that the waste water from the first group won’t be enough pressure to optimize the second group.

If that’s not correct;
Then I should buy a group of 2 canisters and just run the waster into there to get the extra two beds. No pump required. Similar to a BRS 6 stage RODI unit.

Cheers.
Zig

 

[BryanM]

I don't know about a 2nd membrane setup.

But I would suggest you split up the anion and cation resins in to seperate canisters. Most people burn through a lot more of one of them, so the mix beds are somewhat wasteful, and youre already upgraded.

 

[Buckeye Hydro]

It’s my understanding that a second membrane stage will significantly reduce waste water and best optimize water use.
Is this correct?

In most instances users have hard water. Contrary to what you may hear from certain vendors, a second membrane plumbed in series is not a good idea if you have hard water. Unless your intent is to buy membranes more often. If so... please do!

Residential RO Membranes

At Buckeye Hydro we specialize in providing the highest quality water filtration systems and accessories for every potential need.

www.buckeyehydro.com

 

[Freenow54]

It’s my understanding that a second membrane stage will significantly reduce waste water and best optimize water use.
Is this correct?

In most instances users have hard water. Contrary to what you may hear from certain vendors, a second membrane plumbed in series is not a good idea if you have hard water. Unless your intent is to buy membranes more often. If so... please do!

Residential RO Membranes

At Buckeye Hydro we specialize in providing the highest quality water filtration systems and accessories for every potential need.

www.buckeyehydro.com

Thanks for your input . I like to see responses like that or it goes on forever

 

[Seregus]

Sorry can you clarify - you want to add another full 3 stage system on a water you filtered? If so it will not improve waste water. Adding just a second membrane will work and it will reduce waste water, but needs to be installed correctly.

Or please give a bit more info how you are planing to add a second 3 stage system please?

 

[afboundguy]

It’s my understanding that a second membrane stage will significantly reduce waste water and best optimize water use.
Is this correct?

In most instances users have hard water. Contrary to what you may hear from certain vendors, a second membrane plumbed in series is not a good idea if you have hard water. Unless your intent is to buy membranes more often. If so... please do!

Residential RO Membranes

At Buckeye Hydro we specialize in providing the highest quality water filtration systems and accessories for every potential need.

www.buckeyehydro.com

I purchased a second 75 GPD membrane and put it in series (waste line from first RO membrane feeds second RO membrane) and it significantly increased the speed of making water.

Unfortunately I wasn't able to test the waste water but I have 65 psi (adding a booster pump which will help lower waste water as well) and I did put a flow meter on the waste water and it is about 0.13 gallon/min which is about 7.8 gallons/hour. Based on the 150 GPD that's 6.25 gallons/hour so I am pretty close to 1:1 product to waste ratio and I attribute that to the second RO add-on kit.

I am assuming I will get even better ratios when I get time to add the Smart Buddie setup and since I was able to get a flow meter on the waste line I will easily be able to compare.

 

[Buckeye Hydro]

I purchased a second 75 GPD membrane and put it in series (waste line from first RO membrane feeds second RO membrane) and it significantly increased the speed of making water.

Unfortunately I wasn't able to test the waste water but I have 65 psi (adding a booster pump which will help lower waste water as well) and I did put a flow meter on the waste water and it is about 0.13 gallon/min which is about 7.8 gallons/hour. Based on the 150 GPD that's 6.25 gallons/hour so I am pretty close to 1:1 product to waste ratio and I attribute that to the second RO add-on kit.

I am assuming I will get even better ratios when I get time to add the Smart Buddie setup and since I was able to get a flow meter on the waste line I will easily be able to compare.

Chocking off the waste water tube is easy - just a $4 flow restrictor. Just be sure that chocking off the concentrate line is a good idea before you go there.

 

[Ziggy17]

Sorry can you clarify - you want to add another full 3 stage system on a water you filtered? If so it will not improve waste water. Adding just a second membrane will work and it will reduce waste water, but needs to be installed correctly.

Or please give a bit more info how you are planing to add a second 3 stage system please?

It’s my understanding that a second membrane stage will significantly reduce waste water and best optimize water use.
Is this correct?

In most instances users have hard water. Contrary to what you may hear from certain vendors, a second membrane plumbed in series is not a good idea if you have hard water. Unless your intent is to buy membranes more often. If so... please do!

Residential RO Membranes

At Buckeye Hydro we specialize in providing the highest quality water filtration systems and accessories for every potential need.

www.buckeyehydro.com

appreciate your response. What are the specific parameters to determine hard vs soft water? And is there an in between that is not hard or soft? I can get the measurements from my city, but I’d like to have a bench mark as what’s considered hard vs soft for the membrane conversation.

 

[Buckeye Hydro]

I'd say if you have over 34 mg/l (or 34 ppm) or 2 grains per gallon I'd not plumb two membranes in series and approach 50% with your recovery.

 

[Ziggy17]

I'd say if you have over 2 mg/l (or 2 ppm) or 34 grains per gallon I'd not plumb two membranes in series and approach 50% with your recovery.

Copy. Appreciate that. I’ll check with the city services and see where we are at.

 

[Ziggy17]

I'd say if you have over 2 mg/l (or 2 ppm) or 34 grains per gallon I'd not plumb two membranes in series and approach 50% with your recovery.

Here is the water report. I’m not really an expert on how to read it. Seems there are multiple metrics.

 

[Buckeye Hydro]

That's not really the report you need. It doesn't include any info re hardness. But the Mn content is too high for membranes in series. Do you have a whole house softener in place? Or other equipment to treat the Mn?

 

[Ziggy17]

That's not really the report you need. It doesn't include any info re hardness. But the Mn content is too high for membranes in series. Do you have a whole house softener in place? Or other equipment to treat the Mn?

Nothing in place.

 

[Ziggy17]

However, my latest ICP (2 weeks ago) from my RO water showed Mn as near normal.

 

[Ziggy17]

I'd say if you have over 2 mg/l (or 2 ppm) or 34 grains per gallon I'd not plumb two membranes in series and approach 50% with your recovery.

6 grains per gallon as per the city.

 

[Buckeye Hydro]

Do you mean that your RODI water showed no Mn? Or do you mean that your tap water showed no Mn?

6 gpg total hardness would typically not trigger someone to install a softener in their house, but it is too high for membranes plumbed in series with a high recovery (e.g., 1:1 ratio of concentrate to permeate [RO water to waste water]).

Are you noticing brown or black staining in your tubs/sinks/toilets?

Russ

 

[Freenow54]

Do you mean that your RODI water showed no Mn? Or do you mean that your tap water showed no Mn?

6 gpg total hardness would typically not trigger someone to install a softener in their house, but it is too high for membranes plumbed in series with a high recovery (e.g., 1:1 ratio of concentrate to permeate [RO water to waste water]).

Are you noticing brown or black staining in your tubs/sinks/toilets?

Russ

So sorry to change course but I was wondering if you are familiar with the Wats zero waste RO system and your opinion

 

[Buckeye Hydro]

I am. We've been a Watts dealer for decades.

In most situations they do not meet code as they pass the concentrate back into your plumbing. I have a hard time recommending them when I know from the get go they won't meet local code.

 

[Ziggy17]

I got the answer I was looking for. Much appreciated.