When to change DI resin? (1 Viewer)

[Cody]

So I have multiple inline TDS meters so I know exeactly when each canister of resin is exhausted. However, I have a series of DI resin canisters, and they all exhaust in sequence. As the first is exhausted, the second starts working until it’s exhausted, etc.

My question is does anybody know how long you can leave the already exhausted resin in the line before it starts to negatively impact the following chambers of resin?

I’m considering upgrading to six DI canisters just so I can buy the large bag of DI resin and use it all in one sitting, as opposed to leaving it in a ziploc. I hear they start to deteriorate pretty quickly once the vacuum seal has been broken.

 

[Erin]

Once the first is exhausted, I would move the second canister to the first spot (and the third canister to the second spot, etc...) and refill the exhausted canister, placing it at the end of the sequence.
I do the same with my multiple carbon canisters.

*Regarding storage, if you reseal it and keep it in the refrigerator, it is supposed to last 6-8 months without deteriorating

 

[Erin]

Also, from Spectapure,

Continuing to run water through an exhausted DI cartridge results in what is referred to as phospate and silicate dumping. This can actually result in a higher TDS in the water exiting the DI stage than was initially in the RO water and may have disastrous results for your reef tank.

Deionization

SpectraPure, Inc. is an Industry Standard in the Water Purification world. From Drinking Water to Aquarium Systems, you don't just want pure water, you want the PUREST Water! Get it with SpectraPure!

spectrapure.com

 

[decimal]

Just vacuum seal the remainder back up? Changing all resins at once seems pretty inefficient and expensive

 

[Seaworthy Aquatics]

@Erin is correct and it starts to break down pretty quickly once it's fully exhausted and should be replaced as soon as possible. Your end product water will start to smell like a fresh bag of resin when this starts to happen and TDS meters won't always register it right away and still say zero. I've even seen film algae grow quickly in chambers following exhausted resins due to the high phosphates.

 

[Cody]

Gotcha. I am currently running two chambers and the first has been exhausted for a little while. At first when you turn it on, the TDS is higher coming out of the exhausted chamber but it levels back to the same TDS going in pretty quickly.

So in theory, if you’re going to run six chambers, it’s best to split the input to the chambers into six channels then reconnect back to one after the water goes through all six, as opposed to running them in a sequence?

 

[Seaworthy Aquatics]

Gotcha. I am currently running two chambers and the first has been exhausted for a little while. At first when you turn it on, the TDS is higher coming out of the exhausted chamber but it levels back to the same TDS going in pretty quickly.

So in theory, if you’re going to run six chambers, it’s best to split the input to the chambers into six channels then reconnect back to one after the water goes through all six, as opposed to running them in a sequence?

Feed all six chambers simultaneously with one output? Yeah that may work, but I'd be worried about the overall pressure after being split like that. The first few chambers may exhaust faster than the last ones or get some channeling resulting in the same issue with wasted resin. Maybe you could put valves on each chamber, turn them on one at a time and switch to the next chamber as they become exhausted? Or maybe go with larger chambers. Might take some trial and error, but I think you have a few options to make it work. Then I'll steal whatever idea works best! @second_decimal might be right though, and just reseal whatever resin you don't use. I'm trying to redo my own RODI systems so I might have a few ideas worth sharing soon.

 

[decimal]

Imho, the most effective way to implement that part of filtration is to run 3 stages, anion resin, cation resin and a third mixed resin stage. The first stage will always exhaust first but you can treat it the same way you treat your sediment filter. I use .5 micron for primary first stage and then stage 2 and stage (3) 5 micron carbon blocks. I wind up alternating carbon block changes. So I change the .5 filter 2 times and on the second time I replace the stage 2 carbon block. After 3 primary filter changes I change the stage 3 carbon block. Resin works same way. I am not sure what benefits you get from running 2 resin filtration systems concurrently on the same line. The bottle neck in a RO filtration is normally the membrane gph limit, water pressure and temperature. Can u explain?

 

[Cody]

Imho, the most effective way to implement that part of filtration is to run 3 stages, anion resin, cation resin and a third mixed resin stage. The first stage will always exhaust first but you can treat it the same way you treat your sediment filter. I use .5 micron for primary first stage and then stage 2 and stage (3) 5 micron carbon blocks. I wind up alternating carbon block changes. So I change the .5 filter 2 times and on the second time I replace the stage 2 carbon block. After 3 primary filter changes I change the stage 3 carbon block. Resin works same way. I am not sure what benefits you get from running 2 resin filtration systems concurrently on the same line. The bottle neck in a RO filtration is normally the membrane gph limit, water pressure and temperature. Can u explain?

It’s purely a money saving idea. If you buy the individual mixed bed bags of resin then it’s $13.50 per chamber. The big bag costs $60, but has enough to fill six chambers, or $10 per chamber. If you buy them individually then the six bags comes out to $81. My point was, if all else is equal and there’s no negative impact of running six chambers at once, then you’re better off just running six chambers.

Keep in mind, this is based off the 10” canister that I ordered on Amazon being of decent quality. It was $15, as opposed to BRS, which charges $45 for what appears to be identical to the one on Amazon. I’ll get the Amazon one today and inspect it, but I’m guessing it’s the same. It’s not like BRS is manufacturing their own canisters. Both probably came off the same assembly line in China.

Also, as far as running multiple chambers with cation, anion, etc., there’s a calculation that needs to be done, but I think it might not necessarily be cheaper than just running a mixed bed and wasting some media. Yes, the cation and anion don’t waste any resin, but they’re also $16-18 per chamber refill, as opposed to $10 per chamber refill when you buy the large bag of mixed bed. If you knew the exhaustion rates for each scenario then you could calculate that out.

Let’s say in a six month period you use two chambers of anion and one chamber of cation. That’s $48.50, pretax. That’s roughly the same of five chamber refills of mixed bed, assuming you buy the big bag. Would you go through five refills in the time it takes you to do three of the specific beds? It seems like that’s a stretch, not to mention the cost of the extra chambers for cation and anion, which you don’t necessarily need if you just run a mixed bed. However, I realize the $10 per mixed bed is based off of buying the large bag that does six refills and not the individual refill bags, which are $13.50 each.

 

[decimal]

My information about resin setup (anion/cation/mixed) was based on what I think is brs data. So who knows just how accurate that is but probably not designed for you to spend less with them.

On the flip side, I can just cancel Netflix and make up the $$ to run any configuration of resin bed you want.. lol I’m kidding of course but only halfway. Also, if we are being technical here, the hassle of having to fill and replace and maintain 6 resin canisters seems.. like something I would gladly spare a few bucks for if I didn’t have to deal with it. My vote is for bulk resin, vacuum packed, and no more than 3 canisters inline.

Edit: if ur using the same resin in all canisters, I would consider not even bother with 3 and just do 2

 

[Cody]

Here's something else to think about.

Assumed constants:

1) a mixed bed resin has a 50/50 split between cation and anion resin.
2) anion resin is exhausted twice as fast as canion
3) mixed bed resin is $13.49 per refill, anion is $15.99, and cation is $16.49 (all individual refill bags)
4) each additional new canister is $29.99, and the refillable insert for the resin is $7.99, or $37.98 for both


So, let's say that in a twelve month period, you burn through two anion and one cation. Using the first assumption, that means that in the twelve month time frame, you would exhaust four mixed bed refills to remove the same amount of anion, and every time you refilled the mixed bed, then only half of the cation would be exhausted. That means that half of the 50% cation would be good resin that you throw in the trash, aka you're wasting 25% of the mixed bed chamber every time you refill. So, in the same time that you would refill two anion, and one cation chamber, you have to refill four mixed bed chambers to effectively remove the same amount of TDS from your water. I burn through a refill of mixed bed resin about every three months, so this calculation definitely applies to my situation, and means I would need two anion and one cation per year.

I did a breakdown of the time it would take to recoup the initial cost of adding additional chambers versus the savings you get by switching to anion/cation in comparison to just using a single chamber of mixed bed resin. I have a spreadsheet that shows the breakdown, and all the equipment prices are based off of BRS prices. I broke it into two categories: starting with a single DI resin chamber already versus starting with none. Again, these projections are based off of a twelve month window. If you change your resin out more often then the initial investment recoup time would decrease. If you change your resin out less frequently, then it would take longer to recoup the investment. These projections are based off of a twelve month time frame where you would change the mixed bed four times or the 2:1 equivalent of anion and cation. It's a very high demand situation, considering I go through about 225 gallons of RODI water per month. If you make about half as much water per month as I do, then double the time it takes to recoup your investment. Here are the different time frames it would cost to recoup the initial investment: (you save $5.49 per 12 months with my exhaustion/consumption rate)

STARTING WITH NO DI RESIN CANISTERS

ADDING A SINGLE CANISTER WITH MIXED BED
Initial investment plus 12 month supply
-$116.95

ADDING A DUAL CANISTER WITH ANION/CATION
Initial investment plus 12 month supply
-$128.46
Time to recoup initial investment
-2.10 years

ADDING A TRIPLE CANISTER WITH ANION/CATION
Initial investment plus 12 month supply
-$166.95
Time to recoup initial investment
-9.11 years


STARTING WITH A SINGLE DI RESIN CHAMBER

ADDING NO CANISTER WITH MIXED BED
Initial investment plus 12 month supply
-$53.96

ADDING A SINGLE CANISTER WITH ANION/CANTION
Initial investment plus 12 month supply
-$111.46
Time to recoup initial investment
-11.47 years

ADDING A DUAL CANISTER WITH ANION/CATION
Initial investment plus 12 month supply
-$141.95
Time to recoup initial investment
-14.57 years

 

[Cody]

My information about resin setup (anion/cation/mixed) was based on what I think is brs data. So who knows just how accurate that is but probably not designed for you to spend less with them.

On the flip side, I can just cancel Netflix and make up the $$ to run any configuration of resin bed you want.. lol I’m kidding of course but only halfway. Also, if we are being technical here, the hassle of having to fill and replace and maintain 6 resin canisters seems.. like something I would gladly spare a few bucks for if I didn’t have to deal with it. My vote is for bulk resin, vacuum packed, and no more than 3 canisters inline.

Edit: if ur using the same resin in all canisters, I would consider not even bother with 3 and just do 2

The more I look at it, the more I think I'll just use a single chamber of mixed bed. If it is indeed the case that the media deteriorates after it's depleted, then running two mixed beds would be counter-productive. Or at least just run a single anion and a single cation. Based off of my calculations that I just posted, I'd only save about $6 a year switching to the anion/cation method, and that wouldn't justify the initial investment in equipment. It would take me forever to recoup the money.

 

[decimal]

2) anion resin is exhausted twice as fast as canion

By the nature of function the differently charged resins attract different contaminants. If one is depleted faster than the other, it would point to the make up of the water source which can vary wildly. Mixed bed is the most inefficient as one resin can become prematurely depleted while the other is perfectly fine yet both have to be disposed in order to maintain effective function. That is why anion and cation is a minimum and better than just mixed bed. Again, my opinion. I admit I am just too lazy to deep dive into resin costs. All costs are directly tied to the convenience or benefit that I get out of it anyways. What’s worth a lot to me is worthless to the next guy and they would never pay for that.

 

[decimal]

I have been considering a new ATO system for saving a few $$ and not relying on the electrical grid.

 

[Cody]

Feed all six chambers simultaneously with one output? Yeah that may work, but I'd be worried about the overall pressure after being split like that. The first few chambers may exhaust faster than the last ones or get some channeling resulting in the same issue with wasted resin. Maybe you could put valves on each chamber, turn them on one at a time and switch to the next chamber as they become exhausted? Or maybe go with larger chambers. Might take some trial and error, but I think you have a few options to make it work. Then I'll steal whatever idea works best! @second_decimal might be right though, and just reseal whatever resin you don't use. I'm trying to redo my own RODI systems so I might have a few ideas worth sharing soon.

I’m planning something really nice (hopefully it will be)! I’ll have to do drawings soon to post up what I’m thinking about.

 

[Cody]

I have been considering a new ATO system for saving a few $$ and not relying on the electrical grid.

I have been using gravity fed from my tip-off container for five years now and I’ve never had a single hiccup. I highly recommend it!

 

[Cody]

By the nature of function the differently charged resins attract different contaminants. If one is depleted faster than the other, it would point to the make up of the water source which can vary wildly. Mixed bed is the most inefficient as one resin can become prematurely depleted while the other is perfectly fine yet both have to be disposed in order to maintain effective function. That is why anion and cation is a minimum and better than just mixed bed. Again, my opinion. I admit I am just too lazy to deep dive into resin costs. All costs are directly tied to the convenience or benefit that I get out of it anyways. What’s worth a lot to me is worthless to the next guy and they would never pay for that.

I get that. The reason I used anion as an example is because multiple people have told me theirs exhausts twice as fast as cation, plus BRS sells a dual chamber that they label as anion and mixed bed, which hints that typically it goes first. It might be more efficient to use an anion and a mixed bed if you wanted to go the dual route. Or maybe just use an anion and cation.

 

[Cody]

So here’s another question: let’s say I do the three chambers with anion, cation, then mixed bed. Assuming I regularly keep up anion and cation refills, how long can the mixed bed last? In theory, it won’t be really getting much action at all. If the media stays wet then how long will it last, even if it’s not doing any work?

 

[decimal]

Since we are talking about ionization, it involves aligning molecules in a + or - position. My understanding is limited but the mixed bed insures that both polarities are converted back to a natural state.

 

[Erin]

So here’s another question: let’s say I do the three chambers with anion, cation, then mixed bed. Assuming I regularly keep up anion and cation refills, how long can the mixed bed last? In theory, it won’t be really getting much action at all. If the media stays wet then how long will it last, even if it’s not doing any work?

Are you asking if the media will "go bad" in the canister after a while even if it's not exhausted?
(I don't know the answer, but this is a good question for those of us who maybe don't use our RODI as frequently)