RO/DI questions (2 Viewers)

[codesman]

I'm am trying to choose a RO/DI system for my in progress tank. I plan to buy a BRS RO/DI system but there are many options and I have a few questions.

1. Does 4 stage RO/DI give the same quality water as a 7 stage system?
2. Is there a cost benefit for running a 7-stage with the cation and anion refills being cheaper?
3. Any advice for setting up the system?

 

[spsick]

There is a massive cost benefit to using a 7 stage unit with the pro DI 3 stage.

I have to change 1 of the 3 DI stages about once a year. With a 4 stage plan on replacing the DI every month or 2.

I have an 8 stage with the 2 membranes to make more efficient use of water.

 

[zoolan70]

I run separate Cation and Anion resin canisters in mine. I replace the Cation one about every 6 months. I've never replaced by Anion one. In the past, the mixed bed resin lasted a few months at most.

 

[Varig]

More to glom on here. I think technically the water quality can be the same out of a 4 stage, but there is a huge difference in water usage (with 2x RO membranes as @spsick mentjoned) and another massive difference in DI resin usage if you go with the 3 stages of resin (separate cation and anion, followed by a mixed bed). I also run the 3 separate resins after having to change my mixed bed every few months. For me I seem to only use anion resin, so I now haven’t changed my cation or mixed bed in more than 2 years. And the anion last 6+ months.

One point here on the 3 stages of DI, especially given the difference you see between @zoolan70 ‘s experience and my own. What you’ll find is there are 2 types of mixed bed resin that BRS sells. The standard mixed bed has color changing anion beads and the “pro” mixed bed has color changing cation beads. I was told that you should run the mixed bed that corresponds to the separate resin that is depleted first. So in my case I run the standard mixed bed, but I expect @zoolan70 runs the “pro”’mixed bed.

The other thing that I don’t think has been mentioned is the carbon blocks. I’m not sure where you live or if you’ve checked your city water supply (assuming you’re not on a well), but if your city uses chloramine instead of chlorine, I would 100% recommend having the 2 stages of carbon blocks. It’s beneficial for chlorine, but I think more or less “required” if you have chloramine.

So, I guess that gives you some things to at least use to make an informed decision. More questions or thoughts?

 

[asifiqbal2]

I would agree with all that have been said on here. Since how often you change your resin cannot be measured with how many months it takes for you to change them ( it depends on how much water you produce each week and your tank size) I would like to compare notes on the replacement cartridge and how much it cost to replace. I am assuming you guys buy resin in bulk and pack it into the cartridge yourself?
Have you done the math how much each replacement fill cost regardless of what flavor of resin you use ?

Each mixed resin pre filled cartridge cost me $17.75

How much does it cost the other way?

 

[spsick]

@asifiqbal2 I buy the pre-portioned BRS pro resins when it’s on sale and it’s about $15/refill.

 

[asifiqbal2]

Got it! The amount of water I make I would likely have to buy when it’s not on sale too.

$2.75 savings per cartridge using the 3 resin method ( when it’s on sale)

Now I need to do the math of how many cartridges I use in a year

 

[spsick]

Got it! The amount of water I make I would likely have to buy when it’s not on sale too.

$2.75 savings per cartridge using the 3 resin method ( when it’s on sale)

Now I need to do the math of how many cartridges I use in a year

If you’re just using multiple stages of mixed bed, going to the Cation, Anoin, and pro mixed bed you are also going to change cartridges way less often

My tank isn’t much smaller than yours and I honestly only have to touch DI like once a year now. Frees up time and money for me to obsessively replace Prefilter and carbon blocks.

 

[asifiqbal2]

Ok so I used 18 cartridges in a year
So $2.75 savings per cartridge is $50 bucks savings for a year. I made shit tons of water lol

I replace the sediment, carbon and carbon plus every six months. So that is 5 micron sediment, 5 micron carbon and 1/2 micron carbon plus for chlorine and Chloramine for $33.48 combo pack

 

[asifiqbal2]

If you’re just using multiple stages of mixed bed, going to the Cation, Anoin, and pro mixed bed you are also going to change cartridges way less often

My tank isn’t much smaller than yours and I honestly only have to touch DI like once a year now. Frees up time and money for me to obsessively replace Prefilter and carbon blocks.

I just use single stage of DI as mixed bed

 

[Varig]

Right, so I think Ben's point (and it's been my experience as well), is that by splitting the anion/cation you will at "minimum" double the time between cartridge changes. Why? Well it's maybe over simplified, but let's just say the mixed bed cartridge is 50/50 anion/cation. But, as I said before, the only thing that gets depleted in my system (at any significant rate) is the anion. So I was burning up the 50% anion in my mixed bed cartridge is just a few months. BUT, now with them split, I have a 100% cation and 100% anion cartridge. The refill costs the same, but now I'm not paying for 50% cation that never gets depleted anyway. So I wouldn't be surprised if your savings was actually 9x single ion (not sure if you'll be cation or anion) cartridges/year: $15x9 = $135 VS your current $17.75 x 18 = $319.50 or, ~$185/year. And it might even be more, because for whatever reason it doesn't seem like they last 2x as long, it seems like they last 3-4x as long.

Also, the individual ion refills look to be slightly cheaper (~$1/refill). So there is probably a little more in there.

With regard to purchasing on sale, as I understand it the vacuum sealed bags will last a long time, so I usually buy a years worth or whatever anytime they're on sale, to ensure I get the good pricing.

And I guess my final comment, if I ever ended up buying a vacuum sealer, I suspect I'd end up buying the "bulk" bags of resin from BRS, and just immediately repacking them into 1.25 lbs refill packs. I think that drops the refill price to around $10-11 instead of $15.

 

[asifiqbal2]

Nice explanation @Varig
I understood Ben’s explanation after I made the post, the coffee was slowly starting to work.
This makes sense to me, I will look into upgrading my DI to 3 stage. For the amount of water I make it seems worth it !

 

[Reefer Oz]

Great info and discussion!

One other thing to consider is the quality of source water you are filtering. Pretty much every municipality and every well has different water composition. The necessity of any of these stage could be considered. Water quality reports are available from your city and tests of private wells are affordable.

Though I have never followed through with this advice and filter my Duluth city water, which comes in at 40-50tds, through a 7 stage. Other than the sediment filter, all mine get changed yearly on a rotation just because and never get exhausted as far as I can tell.

Many folks could likely get away with just carbon blocks, RO membranes OR DI resins. Or a greatly reduced combination of stages. But with seasonal changes in water quality from any source, contamination from our home plumbing and enough variables in these systems to manage anyway........ hedging our bets and "over filtering" our source water is not a bad idea.

 

[asifiqbal2]

Wow your source water is pretty good!

 

[Reefer Oz]

Duluth water IS Superior water!

 

[asifiqbal2]

No doubt and no pun intended eh?