DI resin question, Crumbletop chime in on it please!

Mikeyjer · #1 12/16/2007, 11:27 PM

Ok, I bought my RO/DI system right before everyone did the group order with airwaterice. I've been making water around 15g or so a week. Water coming out from RO is running at 0-3 tds and coming out from DI at 0 tds. I bought the Extreme 150gpd. The DI resin started changing color about a month after usage, but now the water is running really slow and the DI resin's coloring really browned out and the tds is running around 1-2 coming out from DI. I find a little odd that the DI resin only lasted a short period of time. Let me know what you guys think, I probably would give'em a call first thing in the morning to see if there's something wrong with it or it's running normal......I personally think it's because of the clear housing that's making it exhaust so quick....I might be wrong.....

NeveSSL · #2 12/17/2007, 02:47 AM

Definitely give them a call.

Have you tried backflushing your membrane?

Sounds like it could possibly be your prefilters... but I'm not completely up to snuff with RO/DI.

Also, FWIW, AirWaterIce (notice it didn't censor it?

) is now a sponsor again, so they have a forum. But I don't think Don has a ton of time to answer on there... so you may be best off with a call.

Let us know!

Brandon

crumbletop · #3 12/17/2007, 08:49 AM

Do you have a pressure gauge with that system? If so, where is it reading the pressure? You can use a pressure gauge to tell if the pre-filters are blocked by measuring the pressure where the water enters the first stage, and also just before the RO.

On the DI resin, what is the post RO TDS? The DI may be exhausted, but it also may be that you are making small batches at a time and there is "tds creep". When making smaller batches, the first few gallons of water can have a little blip up in the TDS, so you can also try measuring the TDS right when the unit starts, and then again after it has made a few gallons.

RE the DI resin changing colors, sometimes that is just the resettling of the mixed bed beads, so it is best to go off of the TDS.

I'd give AWI a call, or post in their forum. Something doesn't seem right.

rsteagall · #4 12/17/2007, 09:16 AM

Why would you buy the "Extreme 150gpd"? I don' t believe I've ever read where it was suggested to get anything more than the 75GPD Filmtec membrane. There is much more waste water on anything over the 75GPD membrane from what I understand.

Basically what I believe you are running into is that enough of the resin has been eaten up so that the 150GPD RO membrane is too much. Unless the DI resin is totally exhausted, I think if you slow down the output... you'll get 0 TDS again.

crumbletop · #5 12/17/2007, 10:29 AM

The "extreme" uses a 150 gpd membrane that has 98% rejection so it is similar in rejection characteristics to the 75gpd filmtec that is most commonly recommended. The speed of water output from the membrane doesn't matter as far as the DI is concerned. If the DI can handle say 2000 gallons with an input TDS of 3ppm (I'm making these numbers up), then it doesn't matter how fast the 2000 gallons run through. The slowdown seems more likely to be related to input filters/water pressure/or the restrictor thingy that sits before the membrane.

Mikeyjer · #6 12/18/2007, 01:32 AM

The pressure gauge is running at 75-80 psi so it's doing pretty good. The tds level after RO is running at 0-3 tds and after DI is running at 0-1 tds. The water coming out into the bucket is running really slow, this happened when the DI resin really turned brown brown.....IT didn't take that long after I've had it to turn brown, now it's really brown. I think I've had it running around July or August. I personally don't think it could have exhausted this quick. I forgot to call them today, I'll give'em a call tomorrow.....

Ryan, slow output of what? You can't slow down output at the waste water area because they told me not to do that, it would mess up the system. I can't really slow down the output of the DI water cause it's already slow enough....lol......I'm actually wasting MORE water now to make good water, let's say IF I was wasting 3g to make 1 g of good water, it's at 4-1 or more right now.......

gsusfreak · #7 12/18/2007, 02:03 AM

Quote:

Originally posted by NeveSSL

Have you tried backflushing your membrane?

Brandon

ok maybe i overlooked my manual...but how do you do this?

Mikeyjer · #8 12/18/2007, 02:32 AM

Oh yea, I did do the back flush as well.....It's easy, check in the manual it's there.....

crumbletop · #9 12/18/2007, 07:05 AM

Michael -- try seeing what the flow is from RO only. If it is way faster than the stuff coming out of the DI, then maybe something is somehow clogging the DI. If it is slow as well, then the problem may be on the other side of the membrane. I'd send air water ice an email about this and see what they say.

Mikeyjer · #10 12/19/2007, 12:03 AM

When I called them today, no one answered....So I guess I'll shoot them a e-mail and see what they say.....

Mikeyjer · #11 12/21/2007, 01:11 AM

Well, they called me today assuring me it is ok to use, but just watch the tds levels. They say sometimes when you don't use it days at a time, it can dry out and turn color on you. I guess that's what happened......We'll see.....

BuckeyeFS · #12 12/22/2007, 03:51 PM

Quote:

Originally posted by Mikeyjer
The pressure gauge is running at 75-80 psi so it's doing pretty good. The tds level after RO is running at 0-3 tds and after DI is running at 0-1 tds. The water coming out into the bucket is running really slow, this happened when the DI resin really turned brown brown.....IT didn't take that long after I've had it to turn brown, now it's really brown.

Did your cartridge turn bown in the lower half or the upper half?

Russ

BuckeyeFS · #13 12/22/2007, 03:55 PM

Quote:

Originally posted by crumbletop
The speed of water output from the membrane doesn't matter as far as the DI is concerned. If the DI can handle say 2000 gallons with an input TDS of 3ppm (I'm making these numbers up), then it doesn't matter how fast the 2000 gallons run through.

The permeate flow rate from a 75 and from a 150 gpd are both appropriately low and can be handled by a standard 10 inch DI cartridge. I wouldn't say however that the flow rate through resin doesn't matter - actually contact time/residence time is a critical factor with deionization. That's why we don't route pressurized water from RO storage tanks though a standard 10 inch DI cartridge.

Russ

crumbletop · #14 12/22/2007, 04:48 PM

Thanks, Russ. I meant that in the context of the post I was answering, which was the flow from the 150 gpd isn't too fast.

BuckeyeFS · #15 12/22/2007, 05:02 PM

I'm with you. You're right on.

Mikeyjer · #16 12/23/2007, 12:24 AM

Quote:

Originally posted by BuckeyeFS
Did your cartridge turn bown in the lower half or the upper half?

Russ

The whole thing!

BuckeyeFS · #17 12/23/2007, 04:28 AM

Sounds like it is well past being exhausted...

BuckeyeFS · #18 12/23/2007, 07:56 AM

Didn't see your post above re water draining out of it - that usually looks a lot different that the color change that happens when the resin exhausts.

What's the tds of your DI water?

Mikeyjer · #19 12/24/2007, 12:23 AM

Quote:

Originally posted by BuckeyeFS
Didn't see your post above re water draining out of it - that usually looks a lot different that the color change that happens when the resin exhausts.

What's the tds of your DI water?

0-1

Mikeyjer · #20 12/24/2007, 12:26 AM

But the thing is I got this system back in August. Didn't think it would exhaust this fast....

BuckeyeFS · #21 12/24/2007, 06:30 AM

So you got about 5 months from the DI cartridge - that's not necessarily unusual, depending upon the tds of your RO water and how much DI water you make.

If you do some experimenting with your TDS meter, you'll note that your sediment filter and carbon block filter (collectively called prefilters) do very little to remove dissolved solids. So with your tap water at (for example) 400 ppm, you can measure the water at the “in” port on your RO housing and you'll see its still approximately 400 ppm.

The RO membrane is really the workhorse of the system. It removes most of the TDS, some membranes to a greater extent than others. For instance, 100 gpd Filmtec membranes have a rejection rate of 90% (i.e., they reject 90% of the dissolved solids in feed water). So the purified water coming from your 100 gpd membrane would be about 40 ppm (a 90% reduction). Filmtec 75 gpd (and below) membranes produce less water (aka “permeate”), but have a higher rejection rate (96 to 98%). The life span of a RO membrane is dependant upon how much water you run through it, and how dirty the water is.

Membranes can function well for a year, two years, or more. To test the membrane, measure the total dissolved solids (TDS) in the water coming in to the membrane, and in the purified water (permeate) produced by the membrane. Compare that to the membrane’s advertised rejection rate, and to the same reading you recorded when the membrane was new. Membranes also commonly produce less water as their function declines.

After the RO membrane, water will flow to your DI housing. DI resin in good condition will reduce the 40 ppm water down to 0 or 1 ppm. When the DI output starts creeping up from 0 or 1 ppm to 3 ppm, 5 ppm, and higher, you know that your resin needs to be replaced.

Sometimes people complain that their DI resin didn't last very long. Often the culprit is a malfunctioning RO membrane, or a membrane that is not fully seated, or an RO membrane housing that is cracked - each of these conditions will result in the DI stage receiving “dirty” water. This will exhaust the resin quicker then would otherwise have been the case. Sometimes the problem is poor quality resin, or resin that was not stored properly before use.

What is the tds of your tap water and your RO water?

Russ

fallinapart · #22 12/24/2007, 08:21 AM

Russ, Wow, thanks for that post, I fell like I went to school and actually learned something. Great Post, I have copies & pasted it as that is a keeper for future reference for me.

Norman

crumbletop · #23 12/24/2007, 09:10 AM

Michael,

One other thing related to the flow being less now than when you first installed it. The water temp has gone down around here with the colder weather, and that will affect the water production from the membrane (less water will be filtered at the lower temperature) -- so that may account for the slower flow now than you had in August.

Mikeyjer · #24 12/25/2007, 03:11 AM

Quote:

Originally posted by crumbletop
Michael,

One other thing related to the flow being less now than when you first installed it. The water temp has gone down around here with the colder weather, and that will affect the water production from the membrane (less water will be filtered at the lower temperature) -- so that may account for the slower flow now than you had in August.

Yea I thought about that after I did the post, I remember reading that in the manual.

Mikeyjer · #25 12/25/2007, 03:14 AM

Quote:

Originally posted by BuckeyeFS
What is the tds of your tap water and your RO water?

When I did the test, it was running around 450 if I remember right. The RO is running around 0-3 tds. I just got home from Mid-night mass, I'll try to test the tap again in the morning.