Is there something better than mixed bed DI resin? | BRStv Investigates

randyBRS

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Hey R2R community!

Wow, have we got an investigation for you today! In this week's BRStv Investigates episode, Ryan shares the data we found when testing multiple combinations of DI resins to find out if the standard mixed bed is the best approach to creating ultra pure water for our tanks! :)

Let us know what you think!

 

Rockwall_Reef

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If some particulates only bind in a mixed bed, then what about running cation, anion, and then a mixed resin as a polishing stage?

Just got to it, nevermind
 
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Robert Rainey

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Great Video. You guys at BRS never cease to amaze me. I run the 6 stage RODI unit from BRS and have some issues with water in my area here in texas that this looks like it will finally help. I had close to the same initial city water readings as you do in Minnesota. I'm going to go this route with the extra canister and do as you did here in this video. I'm about to start another aquarium, my dream 400 gallon, actually been working on it for over 2 years collecting the equipment, should finally have water in it in about 2 months. So this was good timing for this video. Thank you!!
 

Randy Holmes-Farley

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Nice study. :)

A couple of comments...

1. You missed (or I missed) the potential huge benefit for some reefers that separate anion and cation resins can be recharged by the user, for substantial cost savings.

2. The comments about sodium having a weak charge and not being removed well by the cation resin for that reason are not entirely accurate. It isn't a poor charge issue as it can be with something like silicate. The issue with sodium (Na+) is that there is a lot of it, and it has a similar affinity to the cation resin as the H+ that it is potentially swapping for. So for that reason, some can get through a pure cation resin if the bed is not long enough to allow for complete binding. Then none is removed in the subsequent anion bed, and sodium hydroxide can come out in the effluent.

Here's a rank order of the affinity of ions for a typical DI:
Hg2+ <Li+ <H+ <Na+ < K+ ≈ NH4+ < Cd2+ < Cs+ < Ag+ < Mn2+ < Mg2+< Zn2+ < Cu2+ < Ni2+ < Co2+ < Ca2+ < Sr2+ < Pb2+ < Al3+ < Fe3+

To be honest, however, none of the explanations given by the DI companies for the sodium leakage happening in dual beds and not in mixed beds makes sense to me. I wish I could be more satisfied with answers that folks give, but they do not seem correct to me and I suspect that something more subtle is causing the issue.

http://puretecwater.com/downloads/basics-of-ion-exchange.pdf

" In a mixed bed system, the strong acid cation and strong base anion resin are intermixed. This effectively makes the mixed bed tank act like thousands of dual bed units in one tank. The cation/anion exchange is taking place over and over within the resin bed. Sodium leakage is addressed because of the sheer number of repeated cation/anion exchanges taking place. By using a mixed bed you can produce the highest quality of deionized water possible."

That doesn't actually make simplistic sense to me as the same could be said of the thousands of cation beads in a dual system.

3. pH measurements in very low TDS water are not going to be accurate without special electrodes. Neither normal pH meters nor kits can accurately measure it, and the result may be mostly noise.

https://tools.thermofisher.com/content/sfs/brochures/AN-PHLOWION-E 0914-RevA-WEB.pdf

That said, the pH after just a cation bed will be low because the resins has swapped H+ for all of the positively charged ions present (say, H+ in for sodium (Na+) coming out). Likewise, the pH after just an anion bed will be very high because the DI swaps in hydroxide for every negatively charged ion present (say, hydroxide in and chloride out).
 
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Zotch

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Great video and got me thinking about spending MORE money!! Ryan looks/sounds a little bit under the weather. Time to put him in the QT!!!!!
 

Bugger

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What would the effect of just running three mixed beds.
Also BrS can you do one on PenTek carbon blocks or have you already done it and found them not as good as the brs version.
Im running three carbon blocks and one di. My di resin seems to last a really long time so Im happy
 

Robin Haselden

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I'll add that in the power plant I work at we use VERY large mixed bed DI resin with cation and anion to clean make up and to polish the water circulating thru our boilers. If it works to make water clean enough for a huge GE turbine spinning 3600rpm that will wreck itself with dirty water...
 

Bronx19

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Great work. But on this one, I'm going to be a party pooper and say its a tonne of work and effort for not a lot of gain. One cartridge, mixed, forget.
 

Scott.h

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This makes me wonder if adding a 2nd canister of mixed resin simply increasing contact time would benefit.
 

120reefkeeper

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This makes me wonder if adding a 2nd canister of mixed resin simply increasing contact time would benefit.

This is exactly what I do. I run dual mixed beds. Once I see the first one exhaust, I remove it and place the second one in the fist chamber and a fresh one in the second chamber.

Works for me.
 
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silvernblackr35

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I would like to give this a shot, my water is pretty similiar to Minneapolis water, 4ppm chloramines and high ph, never tested for silicates.

I do notice an increase in diatoms when the time is getting close to changing my di even with 0tds on my handheld and inline, but it just fixes itself over time. I feel like I waste a lot of di though even with 2 mixed bed canisters.
 

Rick Mathew

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Really great stuff.

Really Appreciate your continued efforts to support the reefing community. It is very valuable

I run dual mixed beds also

Thanks again

Rick
 

Actuarious

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Now BRS just needs to update their product line so that replacement filter kits and add-ons can select the type of resin you want. :)
 

Elgringodiablo

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So, the results for cation and anion single media followed by a mixed bed are pretty dang impressive, but can we see if they outperform two mixed bed canisters? I would hate to add a third canister and buy additional media types to find no improvement.

Also, is this setup doable with the old blue mixed bed color changing DI resin or would I need to switch the 3rd canister to the purple mixed bed? I've got about 6 months worth of the blue stuff in my water shed and it's way too expensive to toss.
 

Bugger

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The test tested pure tap water. It is unlikely that they could get anything more then noise from a dual canister DI RO system. My Di resin takes for ever to change color so I don't see a purpose in changing to a larger system. Thanks to BRS for thinking of this thou
 

Euler Kernighan

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Great read!

Hi Dr. @Randy Holmes-Farley , do you mind if I translate your post above? Reefers on my home country would love to ready and understand these valuable comments of yours. I'll include a link to the original post and credits back to you.

Anyway, thank you for taking time to spread the knowledge and make us understand a bit more of all chemistry involved in our hobby! ;)
 

Actuarious

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I understand all water chemistry is different, but it would be nice to see a study done on the Minneapolis tap water at BRS. How many gallons of product water can be made under the different DI configurations.

Example?
One Mix bed canister - 100 gallons?
Two Mix bed canisters - 120 gallons? before needing the first change

The custom options are a little harder b/c of the different types of media. I would think in an Anion/Mix config and the three canister config, the Anion would be replaced at the same time. However, the Mix in the Anion/Mix config would need to be replaced before the Cation in the 3 config.
 

Randy Holmes-Farley

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Great read!

Hi Dr. @Randy Holmes-Farley , do you mind if I translate your post above? Reefers on my home country would love to ready and understand these valuable comments of yours. I'll include a link to the original post and credits back to you.

Anyway, thank you for taking time to spread the knowledge and make us understand a bit more of all chemistry involved in our hobby! ;)
I sent a report to the Reef2Reef owner to get his input.
 

Ryanbrs

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This is exactly what I do. I run dual mixed beds. Once I see the first one exhaust, I remove it and place the second one in the fist chamber and a fresh one in the second chamber.

Works for me.
One of the benefits a lot of reefers miss on this is when a single DI is 75% exhausted there is only 25% of the contact time. With your approach, you always have a full cartridge of contract time.
 
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