DI Resin usage

[chucklez]

Been super busy with summer winding down and new job, so havent been able to participate as much as I would like, but I have been passively lurking last little while. Shame I missed the swap but it was my wife's grandmother's 100 birthday so was up in Peoria for that.

Anywho, my dilemma. As I have probably complained to some of you, my DI resin usage is crazy. Well, it has gotten worse last few months. Incoming TDS is 437 at this moment. Even with a new 1mic Sediment filter, 2 1mic Chloramine filters and 2 RO membranes (BRS water saver upgrade) I am still burning through a complete resin refill within 150-200g worth of RODI water. And here lately it has gotten worse. Resin isnt cheap. Its gotten so bad I have started recharging my resin just to keep that cost down a bit (doing a large batch right now). FYI little/no change in amount of resin burned from new vs recharged.

Anyone got any ideas? Hell, it would probably be cheaper getting water fills at my LFS, but I am not lugging 10x5g buckets to the LFS every week. Could the flow restrictor coming out of the RO membrane be bad? Im about witts end here

 

[Nanook]

Dig a well?

 

[Crooked Reef]

Is there any way the water is getting past the ro membranes without going through? I’m not real sure how it could bypass both membranes but it wouldn’t hurt to check.

 

[EDJFA]

That sounds like a question for BRS directly. Or one of the other vendors who just does water filtration.

 

[smoothdog]

Try running each RO membrane separately and measuring TDS to see if one is out performing the other. If so, there is the source of your problem.

On a side note, I've switched to running DI resins in separate chambers (cation and anion) followed by a mixed bed as a backup if one runs out. The anion gets used up at least twice as fast as the cation, so if you're running mixed bed solely, you are throwing away or recharging a large portion of unused resin on a regular basis.

 

[Nanook]

Great ideas, Kirk! Never considered doing anion and cation separately.

Chuck, have you checked your very high TDS to see if any one element is out of whack? You could maybe find a particular filter to deal with that one then.

 

[Tigé21v]

BRS did a very informative video on resin usage. Worth watching.
do you know what the CO2 level of your water is? From what I understand, high CO2 in your water will cause you to burn thru resin rapidly

 

[chucklez]

Try running each RO membrane separately and measuring TDS to see if one is out performing the other. If so, there is the source of your problem.

On a side note, I've switched to running DI resins in separate chambers (cation and anion) followed by a mixed bed as a backup if one runs out. The anion gets used up at least twice as fast as the cation, so if you're running mixed bed solely, you are throwing away or recharging a large portion of unused resin on a regular basis.

I have tried changing from the BRS saver to just 1 then the other RO membrane and while it did lengthen a bit the time between changing resin (due to 1/2 the volume being ran through), the actual volume created was pretty much the same. Never tried running anion and cation in 2 separate chambers. I could have done that last night when I was recharging a bunch since they were already separated.

I know I had spoken with my local water provider several years back and they did add Chloramines to the water. Dont remember the exact amount. And I do know that incoming TDS at 400+ is high. I may actually move my incoming TDS meter from before my sediment filter to right before heading into the resin canister. That way I can see how much my prefilters are actually removing. Hmmm...

 

[chucklez]

BRS did a very informative video on resin usage. Worth watching.
do you know what the CO2 level of your water is? From what I understand, high CO2 in your water will cause you to burn thru resin rapidly

Yeah, I watched that video shortly after it came out.

 

[griss]

I was having the same problem earlier this year and, after some research, learned a few new things in my 32 years in the hobby. Here's how I dramatically extended the life of my resin.

1. Our water pressure in the house is erratic. It can fluctuate between 20-60 PSI at my RO/DI system. RO membranes made for the hobby are best at filtering at 80 PSI. So, I added booster pump to my system and calibrated it to 80 PSI. This helped a bit.

2. I also changed to a DI configuration after talking to Kirk about it. Running Cation, then Anion, (or is it the other way around, can't remember right now) then Mixed Bed helped, but I was still burning through one of the resins fairly quickly. That's when I learned about item #3.

3. I had my RO/DI system connected to a float valve in my mixing tub and another float valve in my sump (for top off). Having the RO/DI system "short cycle" or making up very small amounts of water at a time lead to TDS Creep.

Basically what happens is when the system sits idle, TDS will creep back out of the membrane into the water in the membrane housing. When you start the system up again, that TDS laden water hits your resin and depletes if faster. When combined with making small amounts of water frequently (float valve in the sump), it really burns through the DI.

First, I no longer have the system connected to a float valve in my sump. Instead, I have a top off container (20 gallon Brute) that I keep filled and connected to the float valve in the sump.

Second, I installed a fitting between the membrane and DI units that is connected to a valve. Prior to making any water, I open the valve between the membrane and DI and let it run for a while (about 5 gallons). In other words, water is flowing through the membrane, but NOT the DI. When I first open this valve, the TDS coming out of the membrane housing can be as high as 120-150 TDS. No wonder I was depleting DI so fast. After about 5-10 minutes, the TDS out of the membrane is down in the 12-18 range.

Since making these changes, my resin lasts a LOT longer.

 

[smoothdog]

Never thought about adding a diverting valve to purge the creep water, that's a great idea griss!

 

[Tigé21v]

Never thought about adding a diverting valve to purge the creep water, that's a great idea griss!

I have mine set up so that when I start the water, I open two valves- one bypasses the RO production water (to flush the membrane), and the other valve is before the resin.
I start the water, watch the TDS out continue to rise, once they plateau and start to drop, I close the flush valve.
I continue to dump the RO product water until the Out reading is where it should be (1 to 3 ppm for me, depending on the season).
Once at the lowest ppm reading, I close the resin bypass and send the product water to the resin. The whole process usually take two or three minutes.
It works well for me. With the spectraselect 99% membrane and their MaxCap resin, I get 1500 (+/-) gallons out of the first cartridge, easily three times that on the second cartridge

 

[clevername]

Ill chime in and say i have the same problem, i have a booster pump and flush valve. Water going in is 300ish after RO is 12 and after DI is 0
However, i can easily burn through a canaster of DI after 100 gallons.

Anyone know about Kirkwood water and CO2? that would be my only guess on whats going on.

 

[Tigé21v]

Ill chime in and say i have the same problem, i have a booster pump and flush valve. Water going in is 300ish after RO is 12 and after DI is 0
However, i can easily burn through a canaster of DI after 100 gallons.

Anyone know about Kirkwood water and CO2? that would be my only guess on whats going on.

My guess would be Missouri American.
Though maybe you draw from the Meramec around there
Have you tried separate anion/cation, or the MaxCap cartridges?
300 in and 12 out is only 96% rejection. If you get a 98% rejection membrane, you'll immediately double your resin life.