ro/di questions/problems

Arthur1 · 09/28/2009, 09:01 PM

The ro unit has about 70psi going into the 100gpd membrane. Using a 1 micron sediment filter with a one micron carbon block. TDS coming in is 180 leaving membrane is 11. The di cartridge seemed to go very quickly last time. I installed an extra canister for a second di cartridge. First off I know I'm going to hear it, I should switch to the 75gpd membrane?! Also what else can I do to lower the TDS before entering the DI?

aquaman67 · 10/06/2009, 07:19 AM

You are getting about 94 % efficiency from your 100 GPD membrane (which is pretty good for a 100 GPD membrane.)

An average mixed bed DI cartridge should process about 5000 ppm/gallons of ionic load. If all of your load is TDS, and your RO membrane is putting out 11 ppm, then it would process about 5000/11 or about 454 gallons.

If you get a 75 GPD 98 % efficient membrane then the water leaving your membrane will be ~3 TDS.

5000/3 = 1666 gallons.

That's 1212 more gallons.

I've been preaching for years about membrane efficiency. I hope you can see why.

The membrane is just a mechanical filter to take out as much as possible before your DI.

This is why, IMO, you need the best membrane you can get.

Steve71175 · 10/06/2009, 07:54 PM

Quote:

Originally Posted by aquaman67

You are getting about 94 % efficiency from your 100 GPD membrane (which is pretty good for a 100 GPD membrane.)

An average mixed bed DI cartridge should process about 5000 ppm/gallons of ionic load. If all of your load is TDS, and your RO membrane is putting out 11 ppm, then it would process about 5000/11 or about 454 gallons.

If you get a 75 GPD 98 % efficient membrane then the water leaving your membrane will be ~3 TDS.

5000/3 = 1666 gallons.

That's 1212 more gallons.

I've been preaching for years about membrane efficiency. I hope you can see why.

The membrane is just a mechanical filter to take out as much as possible before your DI.

This is why, IMO, you need the best membrane you can get.

What type of unit do you use? I'm in the market for an RO/DI unit and can't decide if some of the more expensive models are worth it.

AaronReeph · 10/06/2009, 07:59 PM

If you have a lot of CO2 in your water source then that would also contribute to the quick demise of DI resin.

aquaman67 · 10/07/2009, 07:20 AM

Quote:

Originally Posted by Steve71175

What type of unit do you use? I'm in the market for an RO/DI unit and can't decide if some of the more expensive models are worth it.

I use a Kent Hi-S that I bought in 2002. I liked it because they had a list by Ion of the rejection rate.

It depends on your source water. If your TDS isn't too bad, then I would choose any of the sponsors here on RC. Air Water and Ice, Buckeye Field Supply, Filter Guys, ect all have similar systems and good customer service.

If your water is horrible then SpectraPure may be your only choice.

aquaman67 · 10/07/2009, 07:22 AM

Quote:

Originally Posted by AaronReeph

If you have a lot of CO2 in your water source then that would also contribute to the quick demise of DI resin.

I agree, that's way I said,

Quote:

Originally Posted by aquaman67

If all of your load is TDS...

Arthur1 · 10/07/2009, 12:52 PM

aqua, thank you for the advise. I was thinking about switching over to the 75 gpd membrane. I just made about 30ish gallons of purified water and about and inch or so of the media has already turned color in the di cartridge. Should I buy the 75 gpd membrane from anywhere or just go to spectras site and get the 90 gpd membrane? The site seems to make theirs seem so much better than anyone elses. Also as far as the di goes I just added a second canister for another di cartidge, should I use a different di media as spectra does when they run dual cartridges. I have no problem buying the media in bulk and mixing my own di cartridges if its worth the money and that much better.

Arthur1 · 10/08/2009, 07:45 AM

anyone?

SpectraPure · 10/08/2009, 05:27 PM

arthur-
thanks for the compliment! fwiw- our spectra select membrane is a tested membrane that we guarantee the rejection/production. Hope this helps you in your quest for ultimate rejection performance. Regarding CO2, you might be able to obtain a municpal report on your content if you are not on a private well. High Co 2 will certainly comprimise DI life as mentioned prior.
As Aquaman 67 has nicely laid out, rejection is a critical factor in your cost to produce DI water. Also is the qualityof DI resin. I would hope you would look at us, or at least one of the other sponsers as a source. If I can be of specifc help please do not hesitate to ask.
bruce

09/28/2009, 09:01 PM	#1
Arthur1 Registered Member Join Date: Oct 2007 Location: Cape Cod MA Posts: 578	ro/di questions/problems The ro unit has about 70psi going into the 100gpd membrane. Using a 1 micron sediment filter with a one micron carbon block. TDS coming in is 180 leaving membrane is 11. The di cartridge seemed to go very quickly last time. I installed an extra canister for a second di cartridge. First off I know I'm going to hear it, I should switch to the 75gpd membrane?! Also what else can I do to lower the TDS before entering the DI?

10/06/2009, 07:19 AM	#2
aquaman67 Registered Member Join Date: Feb 2002 Location: Tennessee Posts: 7,629	You are getting about 94 % efficiency from your 100 GPD membrane (which is pretty good for a 100 GPD membrane.) An average mixed bed DI cartridge should process about 5000 ppm/gallons of ionic load. If all of your load is TDS, and your RO membrane is putting out 11 ppm, then it would process about 5000/11 or about 454 gallons. If you get a 75 GPD 98 % efficient membrane then the water leaving your membrane will be ~3 TDS. 5000/3 = 1666 gallons. That's 1212 more gallons. I've been preaching for years about membrane efficiency. I hope you can see why. The membrane is just a mechanical filter to take out as much as possible before your DI. This is why, IMO, you need the best membrane you can get.

10/06/2009, 07:59 PM	#4
AaronReeph Registered Member Join Date: Oct 2009 Location: Cleveland, Ohio Posts: 220	If you have a lot of CO2 in your water source then that would also contribute to the quick demise of DI resin.

10/07/2009, 12:52 PM	#7
Arthur1 Registered Member Join Date: Oct 2007 Location: Cape Cod MA Posts: 578	aqua, thank you for the advise. I was thinking about switching over to the 75 gpd membrane. I just made about 30ish gallons of purified water and about and inch or so of the media has already turned color in the di cartridge. Should I buy the 75 gpd membrane from anywhere or just go to spectras site and get the 90 gpd membrane? The site seems to make theirs seem so much better than anyone elses. Also as far as the di goes I just added a second canister for another di cartidge, should I use a different di media as spectra does when they run dual cartridges. I have no problem buying the media in bulk and mixing my own di cartridges if its worth the money and that much better.

10/08/2009, 07:45 AM	#8
Arthur1 Registered Member Join Date: Oct 2007 Location: Cape Cod MA Posts: 578	anyone?

10/08/2009, 05:27 PM	#9
SpectraPure RC Sponsor Join Date: Jun 2003 Posts: 0	arthur- thanks for the compliment! fwiw- our spectra select membrane is a tested membrane that we guarantee the rejection/production. Hope this helps you in your quest for ultimate rejection performance. Regarding CO2, you might be able to obtain a municpal report on your content if you are not on a private well. High Co 2 will certainly comprimise DI life as mentioned prior. As Aquaman 67 has nicely laid out, rejection is a critical factor in your cost to produce DI water. Also is the qualityof DI resin. I would hope you would look at us, or at least one of the other sponsers as a source. If I can be of specifc help please do not hesitate to ask. bruce