Why am I burning through DI Resin?

[AZDesertRat]

Bubbling air in a trash can isn't going to do much if anything for you, it needs to be a tall narrow column so all air and water come into cntact with each other. The trashcan has a huge surface area and volume with only a small air supply.
Check out the CO2 degassing column here:
http://spectrapure.com/frequently-asked-questions#calcc02

Notice it is a tall narrow column with the air stone set at the bottom with the RO only water dripping in slowly so the air travels up through the column of water and has lots of contact time to burn off the CO2. This does not happen in a trash can unless you had a air diffuser that covered the entire bottom and huge air pump.
The other thing you find at that link is a nomograph to calculate your actual CO2 content using the pH and alkalinity of your water.

You only listed 2 TDS readings, 58 and 0. You need three readings with an RO/DI, tap water TDS, RO only TDS and final RO/DI TDS to troubleshoot the system.

 

[TheEngineer]

@AZDesertRat thanks. @Downbeach posted a link to that same setup. I'll have to put something like that together.

I did technically list all three, just not together

Input Water: 55-66 (based on spot checks)
RO Water: 3
RODI Water: 0

And interestingly enough, Walmart store brand Distilled water has a TDS of 0. Nuts at $0.78/gal, but a decent backup for me for now. They also have a Primo RO refill station that gets services monthly. The last service on 8/6 showed a TDS of 10. Too high!

 

[TheEngineer]

I'm looking more at this spectrapure diagram and I wonder if I could use the same booster pump to drive the RO side and the delivery up to my DT. Is there any reason I can't just put a couple of valves to switch the water source and output? Do I need to worry about the booster putting too much pressure on the DI resin?

A bucket, a few pieces of PVC and an air pump are things I have already. I'd like to avoid having to buy another pump though...

 

[AZDesertRat]

A RO booster pump is a low GPD/high pressure pump. It takes your existing 40-60 or whatever psi and boosts to up but at only ounces a minute delivery rate. They are not intended to move water around.
I recommend gravity feeding the CO2 column. Disconnect the line between the RO membrane and the DI cartridge and drip the RO water into the column. You can place the column above your DI cartridge and your Brute so it then gravity feeds the CO2 stripped water to the DI then down to the existing trash can storage. The DI will not be under pressure if you degass .

 

[Randy Holmes-Farley Verified Community Expert]

Bubbling air in a trash can isn't going to do much if anything for you, it needs to be a tall narrow column so all air and water come into cntact with each other. The trashcan has a huge surface area and volume with only a small air supply.
.

I don't think I agree with this. It won't happen fast, but it need not. Folks are talking about aerating it for 2 days, that that will work just as well as aerating a trash can of artificial seawater will work.

It will certainly be mixing around well enough with an airstone. The issue is how much air is pumped into it. If you use the same amount of fresh air spread over 2 days of dripping water collection in a tall column or 2 days of aerating a can, it will end up being about the same (IMO), because I think the air bubbles will come fairly close to equilibrating with the nearby water in each case. It won't be completely equilibrated in the few seconds travelling to the top of the can, but we do not need it to be as we can drive air in for as long as needed.

 

[AZDesertRat]

I don't agree. The air is going to travel up and not horizontally so you will have dead spots. In the municipal drinking water industry we run across similar situations in large water storage reservoirs and end up having to install in tank or insitu mixers and baffles to circulate the water and reduce dead spots.
In a trash can you would need a large air pump and airstone to create enough turbulence to get good mixing unless you stirred it up or installed a powerhead/wavemaker too to keep the water circulating

 

[TheEngineer]

@AZDesertRat true. I was hoping to avoid having to wire up a new pump and a pressure switch. Might go back to buckets for some time.

@Randy Holmes-Farley you know I was just thinking about this while I was walking my dog. The spectrapure diagram appears to be making on-demand water available (or at least to some extent). The way it is designed, the water will only be in contact with an airstone while in the tube. I like the idea so I don't have to run an airstone and burn power for 2 days. Ultimately the only way I would know is to test the water. Those kits cost around $40 though and that's too much for me to just do this one test.

I'm wondering where they came up with the 3' tall dimension....

 

[Randy Holmes-Farley Verified Community Expert]

I don't agree. The air is going to travel up and not horizontally so you will have dead spots. In the municipal drinking water industry we run across similar situations in large water storage reservoirs and end up having to install in tank or insitu mixers and baffles to circulate the water and reduce dead spots.
In a trash can you would need a large air pump and airstone to create enough turbulence to get good mixing unless you stirred it up or installed a powerhead/wavemaker too to keep the water circulating

Dead spots in a round can with just water and an airstone? Not if the airstone is anything more than the tiniest trickle of bubbles. It will all be moving around nicely. Sure, some spots may take 30 seconds to recycle around, but that's nothing when we are talking about 2 days of aeration.

 

[TheEngineer]

I don't agree. The air is going to travel up and not horizontally so you will have dead spots. In the municipal drinking water industry we run across similar situations in large water storage reservoirs and end up having to install in tank or insitu mixers and baffles to circulate the water and reduce dead spots.
In a trash can you would need a large air pump and airstone to create enough turbulence to get good mixing unless you stirred it up or installed a powerhead/wavemaker too to keep the water circulating

I'm not in this business, you clearly are, but I'm wondering if the situation you describe has to do with scale. Nature strives for equilibrium. If one "section" of water has less CO2 than the next, the gradient won't stand for long. The CO2 will naturally redistribute to a new equilibrium point. In extremely large systems, I can see this process taking time. But based on volume, it seems like that shouldn't be a problem here.

 

[Randy Holmes-Farley Verified Community Expert]

you know I was just thinking about this while I was walking my dog. The spectrapure diagram appears to be making on-demand water available (or at least to some extent). The way it is designed, the water will only be in contact with an airstone while in the tube. I like the idea so I don't have to run an airstone and burn power for 2 days. Ultimately the only way I would know is to test the water. Those kits cost around $40 though and that's too much for me to just do this one test.

I'm wondering where they came up with the 3' tall dimension....

You still have to do it for 1-2 days if you are making a big trash can full. It fills as fast as the RO fills it, and that is not usually super fast. Certainly the tower will make some water right away, if that is important, and it takes a lot less space.

 

[TheEngineer]

Then something must be missing from their diagram and/or description. They show the column being fed by the RO membrane with an airstone at the bottom. The "degassed" RO water is gravity fed from the top of the tube into the DI resin directly.

 

[habutti]

Bubbling air in a trash can isn't going to do much if anything for you, it needs to be a tall narrow column so all air and water come into cntact with each other. The trashcan has a huge surface area and volume with only a small air supply.
Check out the CO2 degassing column here:
http://spectrapure.com/frequently-asked-questions#calcc02

Notice it is a tall narrow column with the air stone set at the bottom with the RO only water dripping in slowly so the air travels up through the column of water and has lots of contact time to burn off the CO2. This does not happen in a trash can unless you had a air diffuser that covered the entire bottom and huge air pump.
The other thing you find at that link is a nomograph to calculate your actual CO2 content using the pH and alkalinity of your water.

You only listed 2 TDS readings, 58 and 0. You need three readings with an RO/DI, tap water TDS, RO only TDS and final RO/DI TDS to troubleshoot the system.

@AZDesertRat, my apologies if my statement led you to believe that I thought this would work. The message my original post intended was to let the reader know that it was the solution to my issue, in other words it works. Some minds have a hard time accepting simplicity, and have a need to over engineer. I am not saying it is s a bad thing, we need that diversity as human beings. I say it, so we can understand why some get the simple solution and some don't. Another factor could be that we really don't understand what we are doing/trying to accomplish here, or the tools we are using. Again just trying to add clarity. The MJ1200 is a 2-in-1 pump, that can turn 200+gph as per the manufacturer. So as a power head it also has the ability to inject air to the water if you set up the aerator, which I did in addition to dropping an airstone in the barrel. I will match my working solution to your web found design. The trash can be considered as just a reservoir as it is. Your PVC with airstone and the RO drip all happens in the MJ1200, the airstone in the tank is just extra air injected into the system. At 200+ gph the pump can burn off enough CO2 to accomplish this. In my case two days of having that powerhead churning the waters and injecting air at the sames time cures the issue. At that point I convert the MJ1200 from powerhead to delivery pump and with a few quick release connectors it delivers the now CO2 free water to the DI resin depending on how low/high the resin cartridge is you may want to add a valve to trickle the flow through the resin.

Again, I'm not here imagining it might work, I'm telling you it works because I am using the solution.

 

[habutti]

Then something must be missing from their diagram and/or description. They show the column being fed by the RO membrane with an airstone at the bottom. The "degassed" RO water is gravity fed from the top of the tube into the DI resin directly.

So think about this, the most RODI water you can produce with the spectra design is exactly the amount of RO that the membrane delivers, so in a 75 gpd system guess what is the max in theory you can expect to harvest?

 

[Randy Holmes-Farley Verified Community Expert]

Then something must be missing from their diagram and/or description. They show the column being fed by the RO membrane with an airstone at the bottom. The "degassed" RO water is gravity fed from the top of the tube into the DI resin directly.

I'm not disagreeing with that. Did I appear to be? What I am saying is that it will take a substantial period to collect 40 gallons of water that way. So it is not all ready immediately.

 

[TheEngineer]

You still have to do it for 1-2 days if you are making a big trash can full.

I misinterpreted this statement then. I'm thinking along the lines of what @habutti is saying. The water is produced so slowly that it should have ample time to get aerated before gravity takes it to the DI resin.

 

[Randy Holmes-Farley Verified Community Expert]

I misinterpreted this statement then. I'm thinking along the lines of what @habutti is saying. The water is produced so slowly that it should have ample time to get aerated before gravity takes it to the DI resin.

Yes.

 

[gws3]

I have first hand experience with this exact problem and resolving the issue, so maybe I can assist. When I bought my house a few years ago my well water was also burning through DI resin. I would only be able to make about 50-100 gallons per cartridge.

I looked into the issue and concluded it must be excess CO2 in the well water. My water making station now consists of three 100 gallon containers. One ELEVATED container that contains output from the RO membrane and sediment filters. The second container is on the ground level and has the output from the DI resin. The third is on ground level and is for mixing salt water.

I run a booster pump at 80 psi and two 75 GPD membranes. Well water goes in at ~47 ppm TDS, and out of the sediment filters and RO membranes at about 3 ppm TDS into the elevated container. In the elevated container I have an airstone at the bottom and a typical hobby grade air pump. I just let the air pump run 24/7.
It is then gravity fed through the DI resin into the bottom container. The resin reduces it from about 1 ppm TDS (I guess it reads lower without excess CO2) to 0 ppm TDS. A float valve at the top keeps the container from over filling.

With this set up there is no waiting for the water in the elevated container to aerate. I run the air pump 24/7, and turn on the RO system for the day when needed. It constantly drains through the DI resin on demand. The RO system produces water slowly enough that levels of CO2 that would deplete the resin never occur.

So basically you just need a significant sized holding container prior to the resin that is aerated with a cheap air pump and air stone. My resin consumption has now gone from only producing 50-100 gallons to lasting about 6 months.

 

[TheEngineer]

Thanks for sharing your experience. My preference is not to keep quite so much volume on hand at all time. I'm good with 5g on hand and ready to use. The gravity fed option seems like a good approach. The spectrapure design has water just trickling out of the aeration column and down to the DI resin via gravity too.

 

[Irsug1]

I have to degas as well. I use the avast marine diaphragm pump it's a little noisy but super powerful. It can handle a lot of head pressure too.

 

[habutti]

Yup, degassing is the only way to combat this either manually with a paddle if you don't want to use power (which is insignificant), or embrace technology. Any pump will do it, the one you choose depends on how fast you want the job done, and your budget of course.