View Full Version : DI cartridge life expectancy
75gal
08/16/2015, 08:32 AM
I have a Spectrapure 90gpd RO/DI unit and it seems like the DI cartridge only lasts a month or so...is this average or is my less than recommend water pressure of 40psi to blame? Thanks
Tom
ksicard
08/16/2015, 08:40 AM
I have a 75GPD unit with only 30 PSI going through it and my DI cartridge runs for about 10-11 months.
ericarenee
08/16/2015, 08:50 AM
There is no Average...
The life of the Di resin depends on two things
The TDS Value of water going into resin
The Amount of water you are Filtering.....
azjohnny
08/16/2015, 08:53 AM
If the filter is properly installed in the canister it will depend on how much water is made and the incoming TDS to the DI
After my membrane I have 7 TDS , I make about 100 gals a month and my Max Cap DI lasts 6 months and the Silica Buster DI every 3rd Max Cap change
The higher the water pressure the better. The higher pressure will produce more water and have lower TDS levels. I run my Max cap @ 100 psi and get 160 gpd from a 90 gpd membrane
markalot
08/16/2015, 08:53 AM
I have a Spectrapure 90gpd RO/DI unit and it seems like the DI cartridge only lasts a month or so...is this average or is my less than recommend water pressure of 40psi to blame? Thanks
Tom
Something is wrong with your RO membrane IMO.
Water comes from the tap, passes through a sediment filter, then a carbon block, and then into the RO membrane. The RO should reduce the TDS down to 1 to 3 so the DI only has to work to remove what's left. If the RO membrane has a tear or there's something in your water destroying the membrane then TDS in to the DI will be too high and it will rapidly exhaust.
You need to test TDS coming out of the RO membrane to see if that's the issue and then look into fixing it.
For my spectrapure system, I replace sediment and carbon blocks every 6 months, DI once a year or longer if it looks ok and still tests 0 with a temperature correcting TDS meter.
azjohnny
08/16/2015, 08:55 AM
I have a 75GPD unit with only 30 PSI going through it and my DI cartridge runs for about 10-11 months.
40 psi the minimum that is suggested by any manufacturer, I wouldn't run a RO/DI at less than 60 psi. By running at a low pressure you will also prematurely foul the membrane
Breadman03
08/16/2015, 08:56 AM
What is your RO membrane rejection rate? What is the TDS of the water going into your membrane, and what is coming out?
I was getting about 60 gallons of DI before my DI was exhausted on my original membrane. I upgraded from the standard BRS to a 99% Spectrapure membrane and now get tons of water. As in I change it so infrequently that I don't remember how long it's been, but less than a year, and I make somewhere around 90-100 gallons per week between WC and ATO needs.
75gal
08/16/2015, 09:36 AM
I got 225 coming in 11 out of the RO and now (spent DI) I get 1 out od the DI
markalot
08/16/2015, 10:10 AM
RO membrane is bad IMO, 11 is too high. How old is the membrane? Is this with the built in TDS meter? If so then it's reading low, especially if the water is cold.
cambo123
08/16/2015, 10:13 AM
I almost get that with incoming TDS of 800. You need a booster pump. You should have less then 5 TDS out of your membrane
shifty51008
08/16/2015, 10:37 AM
Deff gonna want a booster pump and maybe a new membrane. Im running the MAXR ro membrane from buckeye hydro with a water pressure of 60psi. My tap is 531ppm and pre di is 4ppm
75gal
08/16/2015, 01:11 PM
It's gotta be 5months old....oh well. I'll look into getting a new membrane and a booster.
Breadman03
08/16/2015, 01:20 PM
You should contact Spectrapure or Buckeye. Both are forum sponsors and will work with you to make a sound investment in your system without just parts swapping.
azjohnny
08/16/2015, 01:21 PM
You might have an issue with CO2. This would cause the DI to deplete prematurely
slief
08/16/2015, 03:29 PM
The life of the DI cartridge has little to do with the incoming TDS. It's not the actual TDS that matters as much as what makes up those dissolved solids in addition to and most importantly what else is in the water. In your case, I'd bet your RO membrane is or was just fine contrary to Markalot's suggestion. Water pressure impacts the rejection ratio of the RO membrane which can have an impact on the longevity of the DI membranes but that is only part of your issue.
The things I would be focused on which most certainly are at the root of your issue is what's in your water. TDS can be made up of all kinds of things. Some of which isn't a big deal while others can kill the cartridges fast. Some if removed by the RO membrane, sediment filter and carbon blocks. On the other hand, the things you should be most concerned with would be Co2 (as mentioned), Chloramines and in some cases, chlorine depending on the concentration. Co2 and Chloramines both can kill your cartridges in a hurry. If you are on well water, Co2 can be a big problem. Some municipalities but not all use chloramines as part of the water purification process and chloromines are a huge problem when it comes to your water filter and are one of the main causes of premature cartrdige life when it comes to city tap water. Typically water quality reports will disclose the use of chloromines. If you have them in your water, that is likely your issue and you will likely need a carbon based prefilter to remove that stuff before the membranes. You can google the water quality report for your city to see if they are present.
That said, 40psi is pretty low and if I were in your shoes, I would also be considering a booster pump as that too will go a long way in improving your rejection ration and longevity of your cartridges.
FWIW, I run a Spectrapure MaxCap 90GPD 1:1 unit. It has a booster pump and my tap water runs between 475 and 575 TDS. I get upwards of 1000 gallons out of my first stage DI cartridge and even more out of the 2nd stage DI despite my high TDS and 1:1 water to DI water ratio. I would expect that with the addition of a booster pump and addressing the source of your DI cartridge exhaustion, you should be able to get several hundred gallons out of your DI cartridges provided you solve that issue. As I said, I highly doubt your issue is your membrane but instead, what's in your tap water.
Download your water quality report and contact Spectrapure. They will check out your water quality report and help you determine the best course of action to improve your cartridge life.
markalot
08/16/2015, 04:05 PM
40 PSI is low but at the bottom of the accepted zone. I think whoever said CO2 is probably right since, according to the spectrapure faq, co2 is the most common cause of early DI exhaustion. I'd get a co2 test done before spending any more money on the unit, IMO.
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