Water purity equipment questions

GPhiAce · 12/19/2008, 09:23 AM

So, I have a few basic questions I believe.
What is the benefit of having a dual stage DI added to a 4 stage RO unit???? What is the difference between a dual TDS meter and a single TDS meter???? What are the 4 stages in a 4 stage RO unit with 3 chambers???

AZDesertRat · 12/19/2008, 11:07 AM

The benefit of the DI is 0 TDS water. An RO will only do 90 to 98% of the filtration, the DI does the final polishing to get what the prefilter, carbon and RO miss.
Dual inline TDS meters are just that, a dedicated meter with two probes which can measure TDS from two different points, normally they are installed to read the post RO TDS and the final RO/DI TDS. While I have two of the dual inline TDS meters, I much prefer a good handheld TDS meter due to increased accuracy and its portability. Its nice to be able to test water out of your tap, from the grocery store, LFS, your RO storage container, the neighbors etc. and with an inline you lose that capability, thye are dedicated and cannot be used portable since thye rely on water movement past the probes to work.

RO configurations will vary from vendor to vendor but the two most common arrangements are
1. Prefilter- usually 5 to 10 microns
2. Coarse carbon block or sometimes GAC in less expensive units
3. Lower micron carbon block
4. RO membrane

A better system will be more like this:
1. Prefilter- 1 micron or less, better units use 0.5 or even 0.2 micron pleated prefilters with 10x the surface area
2. Carbon Block- a single 0.5 or 0.6 micron 20,000 gallon Chlroine Guzzler type carbon is all you will ever need, even for chloramines
3. RO membrane
4. DI- usually a full sized 10" vertical canister like the prefilter and carbon block are in.

SDome vendors still insist on using two carbons but this is old technology and a waste of money. Both prefilters and carbon have been greatly improved over the last several years to the point where carbon that used to only last 300 gallons may now last 20,000 gallons. Prefilters are also in the sub micron range today so even though they filter to a much smaller level they produce less backpressure, last longer and do a better job of protecting the downstream carbon block and RO membrane so they both work better and last longer.

Dual DI has advantages especially if they are full size vertical canisters, the little horizontal tubes do not function nearly as well due to short circuiting and channelling. With dual DI you get more contact time plus if you have one of the dual inline TDS meters you can monitor each DI seperately and when the first one starts to exhauste you can remove it, move the second one into the first position and install a fresh one in the second position to get longer life. Other options which is what I do is to use different DI cartridges for different purposes. I use the Spectrapure MaxCap DI in the first position and their SilicaBuster in the second position. I get about 5 times the life out of my MaxCap cartridges and 15 or more times the life out of my SilicaBuster by doing this. Where normal mixed bed DI resin lasted me 150 gallons per 20 oz cartridge I now get 830+ gallons on a MaxCap and 2500+ gallons on a single SilicaBuster.

GPhiAce · 12/19/2008, 01:24 PM

Great info. Thanks a bunch

12/19/2008, 09:23 AM	#1
GPhiAce Registered Member Join Date: Aug 2007 Location: CoMo Posts: 1,615	Water purity equipment questions So, I have a few basic questions I believe. What is the benefit of having a dual stage DI added to a 4 stage RO unit???? What is the difference between a dual TDS meter and a single TDS meter???? What are the 4 stages in a 4 stage RO unit with 3 chambers???

12/19/2008, 01:24 PM	#3
GPhiAce Registered Member Join Date: Aug 2007 Location: CoMo Posts: 1,615	Great info. Thanks a bunch __________________ Paul Professional Bum Current Tank Info: empty 120 gallon glass box. wanna help fill it? sps and palys please

12/19/2008, 11:07 AM	#2
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	The benefit of the DI is 0 TDS water. An RO will only do 90 to 98% of the filtration, the DI does the final polishing to get what the prefilter, carbon and RO miss. Dual inline TDS meters are just that, a dedicated meter with two probes which can measure TDS from two different points, normally they are installed to read the post RO TDS and the final RO/DI TDS. While I have two of the dual inline TDS meters, I much prefer a good handheld TDS meter due to increased accuracy and its portability. Its nice to be able to test water out of your tap, from the grocery store, LFS, your RO storage container, the neighbors etc. and with an inline you lose that capability, thye are dedicated and cannot be used portable since thye rely on water movement past the probes to work. RO configurations will vary from vendor to vendor but the two most common arrangements are 1. Prefilter- usually 5 to 10 microns 2. Coarse carbon block or sometimes GAC in less expensive units 3. Lower micron carbon block 4. RO membrane A better system will be more like this: 1. Prefilter- 1 micron or less, better units use 0.5 or even 0.2 micron pleated prefilters with 10x the surface area 2. Carbon Block- a single 0.5 or 0.6 micron 20,000 gallon Chlroine Guzzler type carbon is all you will ever need, even for chloramines 3. RO membrane 4. DI- usually a full sized 10" vertical canister like the prefilter and carbon block are in. SDome vendors still insist on using two carbons but this is old technology and a waste of money. Both prefilters and carbon have been greatly improved over the last several years to the point where carbon that used to only last 300 gallons may now last 20,000 gallons. Prefilters are also in the sub micron range today so even though they filter to a much smaller level they produce less backpressure, last longer and do a better job of protecting the downstream carbon block and RO membrane so they both work better and last longer. Dual DI has advantages especially if they are full size vertical canisters, the little horizontal tubes do not function nearly as well due to short circuiting and channelling. With dual DI you get more contact time plus if you have one of the dual inline TDS meters you can monitor each DI seperately and when the first one starts to exhauste you can remove it, move the second one into the first position and install a fresh one in the second position to get longer life. Other options which is what I do is to use different DI cartridges for different purposes. I use the Spectrapure MaxCap DI in the first position and their SilicaBuster in the second position. I get about 5 times the life out of my MaxCap cartridges and 15 or more times the life out of my SilicaBuster by doing this. Where normal mixed bed DI resin lasted me 150 gallons per 20 oz cartridge I now get 830+ gallons on a MaxCap and 2500+ gallons on a single SilicaBuster.