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Eel Freak
07/31/2010, 06:45 PM
DI resin, what's the full story? At work, I have a twin RO/DI unit to the current unit I have at home and both achieve a TDS of 8 after the membranes (trio of DOW/FilmTec 75GPD) but before DI under different conditions and temps. However, my unit goes through about 45-60 gallons before consuming an entire DI canister. At work, I can make around 200 gallons on a single canister?? The only difference is that the one at home uses softened well water and the one at work uses city water that has been decholorinated. Even the TDS on the feed line is nearly the same and the DI resin is all from the same bulk batch. The units are literally twins so this is a major dilemma to me... Any input here is greatly appreciated, thanks!
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Buckeye Hydro
08/01/2010, 04:01 AM
Hmm. Interesting. Its likely the difference is due to the differnt feedwater at the two locations.

My guess is that your home system is dealing with high CO2 in the feedwater. Can you get a measure of the alkalinity and pH of the RO water at both locations?

Russ

Eel Freak
08/01/2010, 07:16 AM
Oh.... That's an interesting point, I forgot about CO2 concentration. I'll measure both this afternoon and post.

AquaPete
08/02/2010, 09:36 AM
I would also check the final TDS. I have seen water conditions that would falsely trigger the pH indicator on the DI resin (have had this strange occurence happen mostly on well water)

If the TDS is Zero leaving the DI - than its the pH color indicator messing with us

if the TDS is not Zero, and is more like the RO water (8ppm) than we will have to look elsewhere..

keep us 'posted' :fun4:

Eel Freak
08/02/2010, 01:39 PM
Ok, didn't get the readings from work but my pH is 7.2 with a dKH of 15 so if I'm correct that's 28ppm CO2. The TDS leaving the DI resin is zero. Both meters read that so I feel it's accurate. Source water is about 300.

Buckeye Hydro
08/06/2010, 04:26 AM
Right.

So with that level of co2 you should see about a couple of hundred gallons through the DI before it needs to be changed.

Russ

Buckeye Hydro
08/06/2010, 04:27 AM
I would also check the final TDS. I have seen water conditions that would falsely trigger the pH indicator on the DI resin (have had this strange occurence happen mostly on well water)

If the TDS is Zero leaving the DI - than its the pH color indicator messing with us

if the TDS is not Zero, and is more like the RO water (8ppm) than we will have to look elsewhere..

keep us 'posted' :fun4:

Welcome to the Buckeye Field Supply forum Pete!;)

Eel Freak
08/06/2010, 08:59 AM
So with that level of co2 you should see about a couple of hundred gallons through the DI before it needs to be changed.

Russ

Herein lies the problem, I only can make about half that. It's not a nightmare since I recharge my resin, but I still find it odd. I hadn't thought of it previously, but could the fact that on my unit I separated my resin beds in a 50/50 ratio and at work I just use them mixed? I had seen the same results even before switching to separate beds. Also, if my resin turns out not to be the same ratio as when it's mixed, would that affect how long it would last?

Thanks for all the help as I'm not entirely knowledgeable on the deionization front.

Buckeye Hydro
08/06/2010, 11:29 AM
The plot thickens....

In a typical mixed bed resin, its not a 50/50 mix of cation with anion. More like 60% anion to 40% cation.

Also - it may be that you are not getting a full charge on the resin.

You'll see better treatment with a mixed bed resin relative tho the same volume of cation and anion beads in separate beds.

Russ

Eel Freak
08/06/2010, 12:13 PM
Okay, so I found out more regarding my specific resin. The mixed resin I buy and then separate begins at 50% anion to 50% cation. So I am okay on that front. Additionally, as a control, I tried new resin that had not been recharged by me and compared how long it lasted with my recharged resin. The results were the same if not the recharged lasted a little longer.

Buckeye Hydro
08/06/2010, 01:02 PM
What resin are you buying?

Eel Freak
08/07/2010, 02:31 PM
What specifically do you mean? I'll call my distributor on Monday if I know what to ask...

Buckeye Hydro
08/07/2010, 04:27 PM
What brand of resin is it? What is the product name/number?

Rwinfrey
08/10/2010, 05:03 PM
I was Pete's headache with the well water and let me tell you I am glad we figured it out. I was getting nerviuos my ro water was going to run me big $$$ but after monitoring it for long periods of time this was are conclusion. I also think I had a little TDS creep my retrictor was bad and my ASO would never completly shut down making my ro start and stop alot.