Why am I burning through DI Resin?

[TheEngineer]

I'll look into picking up another TDS meter. I'd imagine the readings would skew somewhat symmetrically so if I'm reading say half of what it really is, I'm still putting out around only 2-4PPM from my RO.

I can check the kit and see if it does both.

As to the test timing, the dates and times were within a day or two of the draw date (as per the report) if memory serves. The results took two weeks to get to me. The only thing on there they told us to be concerned about was the lead. As to the temp of the sample, I'm a little dubious. They took the sample from my master bath tub (why not from where the well comes in is beyond me). I'd be surprised if it was still that cold when it came out.

 

[TheEngineer]

Just wanted to post a quick update to this thread. I've been doing some more experiments to see what if I can find any patterns.

I definitely am not going through as much resin now that I'm degassing. I wanted to see if I needed to degas for longer so I put a 5g bucket together with a push-connect drain on it so I could run 5 gallons at a time. I run the airstone for a couple of days now and I see even less usage of the DI, but definitely more than I should be. I'd say I can probably get about 100 gallons per canister now. It should be way more than that though. Someone posted a link to a SpectraPure CO2 test kit. It's only $20 so I might grab it just to see what the levels are really.

 

[TheEngineer]

Back again!

I finally got my well water checked out to see what my source looks like. I'm waiting on the metals (iron, manganese and lead), but I got the rest. Here are my results:

Turbidity: 0.49 (<5 EPA Standard)
Color: 1 (<15 Color Units EPA Standard)
pH: 5.8 (6.5-8.5 EPA Standard) <-- Needs attention
Nitrate: 3.92 (<10mg/L EPA Standard)
Chloride: 5.0 (<250mg/L EPA Standard)
MBAS: undetectable (<0.5mg/L EPA Standard)
Hardness: 66 (<500mg/L EPA Standard)
Total Coliform: 0 (don't know the standard)

At this point, it looks like pH is my only big problem for now. That's easy enough to take care of. Since it is so low, I couldn't do soda ash injection and I'd have to go to calcite. I'm not sure how much hardness that will add to my water though. I'll have to look up the calculation.

 

[dewboy1127]

Didnt read through every page of post but i did have di resin go out a bunch after my membrane took a crap

 

[TheEngineer]

Didnt read through every page of post but i did have di resin go out a bunch after my membrane took a crap

After some trial and error, we came to the conclusion that I have high CO2 levels in my water. The CO2 blows past the RO membrane, but gets eaten up by the DI. Aerating the water for 24 hours seems to greatly reduce the consumption. It is still a bit high, but I can't visibly watch the DI get depleted as it runs now. I lose about 1/8" per 5 gallons I make.

 

[red reef]

you should do what I did. I put a bleeder valve between my ro membrane and my DI container. I open it when I first turn it on and let the TDS meter run down till about 10 ppm. then close it and open the line to my RODI tank. that has saved me a ton of DI resin because the TDS iv very high when you start making water.

 

[TheEngineer]

you should do what I did. I put a bleeder valve between my ro membrane and my DI container. I open it when I first turn it on and let the TDS meter run down till about 10 ppm. then close it and open the line to my RODI tank. that has saved me a ton of DI resin because the TDS iv very high when you start making water.

Thanks for the suggestion. TDS isn't my problem. It is 65 out of the well and 1 when it comes out of the RO stage.

 

[TheEngineer]

Got my full test results back. Turns out I don't have lead. I'm a little concerned why my first test showed it though. I did a first draw test too and that showed 0 also.

The only thing that is off, from these tests, is my pH. Water is pretty soft at 66.0, no other high metal levels. I bought a pH neutralizer which will be here in a few weeks. What are the chances that pH (CO2 by extension) is my only issue? It would be great to get rid of the buckets in my basement and be hooked right up to the RODI system.

@Randy Holmes-Farley, @AZDesertRat, @kschweer @gws3

 

[rayn]

@icecool2 can you post a pic of your set up? Interested in what you did.

 

[TheEngineer]

This is the first setup I made. It worked, but I was still burning through resin faster than I should be.

https://www.reef2reef.com/threads/diy-co2-degassing-chamber-for-ro-di.212587/

 

[Xtc_link]

Ever get the co2 test kit? I never ended up picking one up myself. I did get a decent ph pen and cal solution. On my chamber I get ph to go from 5.8 to 6.8 using the cheap blue air stones. Only two at the moment.

Ever get a link for better diffusers? I'm looking at bubblemacairdiffusers.com. Not sure though, lol

 

[TheEngineer]

Nope, I didn't. I haven't checked pH, but I don't go through resin now that I aerate for 24 hours. A new airstone would probably help. I use the cheap blue ones.

 

[christwendt]

Hi calcium levels will not effect the membrane to my knowledge. I have never had a issue with my RO membrane at all. However, hard water will wipe out the DI resin extremely fast. You don't have to buy a water softener. You can have a company come out and install a softening tank for you. They will come out once a month and replace the tank that has been recharged. I pay 40 a month and installation was free!
You need to test the well water with a calcium test kit to see what numbers you get.

Can someone elaborate on this? I just moved to a house with a water softener that I was told I need to add salt to ? It still has some in the salt bin now. But my di resin is burning like crazy making new water at my new place. The tds is 625 out the tap.. what do I do ?

 

[DCR]

Water softeners need to be regenerated periodically with salt. You can do it on site (like the system you apparently have), or you can just have a company come out and exchange your resin bed for a regenerated bed and they will regenerate the resin offsite.

That is a lot of TDS. Do you know the TDS coming out of the RO unit? I would guess you would need a high reject rate on the RO for that much TDS.

Well water frequently has a lot of CO2 which will not be removed by the RO, but is removed by the DI (anion) resin. You can get a pretty good idea how much CO2 you have by testing the pH and the alkalinity of the water. A low pH with high alkalinity indicates high CO2. There are some charts in the freshwater texts the relationship. To remove the CO2 you need to let the water degas ahead of the DI unit which is what is described in this thread. You can add some drip type packing as well to help it degas.

 

[christwendt]

Water softeners need to be regenerated periodically with salt. You can do it on site (like the system you apparently have), or you can just have a company come out and exchange your resin bed for a regenerated bed and they will regenerate the resin offsite.

That is a lot of TDS. Do you know the TDS coming out of the RO unit? I would guess you would need a high reject rate on the RO for that much TDS.

Well water frequently has a lot of CO2 which will not be removed by the RO, but is removed by the DI (anion) resin. You can get a pretty good idea how much CO2 you have by testing the pH and the alkalinity of the water. A low pH with high alkalinity indicates high CO2. There are some charts in the freshwater texts the relationship. To remove the CO2 you need to let the water degas ahead of the DI unit which is what is described in this thread. You can add some drip type packing as well to help it degas.

Thank you for the response. I will test the water for C02 later today. I understand how to remove the C02 by letting it sit and put a power head in a bucket. How would I push that rodi in bucket through filter after it has degassed? Wouldn’t I still have waste water then.

 

[DCR]

Thank you for the response. I will test the water for C02 later today. I understand how to remove the C02 by letting it sit and put a power head in a bucket. How would I push that rodi in bucket through filter after it has degassed? Wouldn’t I still have waste water then.

You will need some type of low capacity pump to push it through the resin cannisters. I would probably look at something like a small Sicce Syncra. It should not take much head. I would have a valve to throttle the flow on the outlet of the DI cannisters to limit the flow through the resin. If you elevated the bucket you might be able to even just gravity flow through the DI resin.

You are still going to have the same waste water from the reject stream of the RO unit. That will not change.

I also meant to add that I don't think softeners do anything to really help control TDS. All you are doing is exchanging Calcium and Magnesium cations for sodium cations. It may allow you to run with less reject water since there will be less tendency to scale in the RO, but that is about the only benefit. Sodium is actually removed less effectively by an RO than calcium or magnesium.

 

[MPCReefer]

Water softeners need to be regenerated periodically with salt. You can do it on site (like the system you apparently have), or you can just have a company come out and exchange your resin bed for a regenerated bed and they will regenerate the resin offsite.

That is a lot of TDS. Do you know the TDS coming out of the RO unit? I would guess you would need a high reject rate on the RO for that much TDS.

Well water frequently has a lot of CO2 which will not be removed by the RO, but is removed by the DI (anion) resin. You can get a pretty good idea how much CO2 you have by testing the pH and the alkalinity of the water. A low pH with high alkalinity indicates high CO2. There are some charts in the freshwater texts the relationship. To remove the CO2 you need to let the water degas ahead of the DI unit which is what is described in this thread. You can add some drip type packing as well to help it degas.

What is considered high Co2? I tested at 11 ppm and I burned through a mixed resin filter in about 100 - 120 gallons of RODI.

 

[DCR]

That is higher than normal equilibrium with air which I think is about 2-3 ppm (like surface water). You can think of it as just adding 11 ppm to the TDS you measure coming out of your RO. The TDS meters do not include CO2 in their measurement. I would have to study the type of resin and how much the anion resin can theoretically hold to say whether 100-120 gallons is within the ballpark, but offhand I would guess it probably is.