RO filter ?

jbittner · 02/26/2007, 10:10 AM

I just replaced my RO filters and I thought I should do some testing. My results were interesting. I have a 6 stage RO/DI that I have had for a few years.

Tap H2O= 348
before RO=338
Post RO=20
Post DI=0

The number that concerns me is the before RO 338. I thought the sediment and carbon would remove more that 10 tds. I use the before RO water for drinking and thought the TDS would be lower. I am also concerned about RO life with so much TDS hitting the membrane.

jbittner · 02/26/2007, 11:44 AM

^

AZDesertRat · 02/26/2007, 12:14 PM

Prefilters remove sediment or suspended solids (TSS-Total Suspended Solids) not dissolved solids(TDS-Total Dissolved Solids). Carbon blocks remove chlorine and volatile organic chemicals (VOCs). Its the membrane that is the workhorse and removes the dissolved particles that are in the microscopic or even atomic range, much much smaller than suspended solids.
How old is the membrane, what brand and model is it and how long did you let the water run before testing the TDS?
20 is not very good at all especially if its a new membrane, it should be about 6 or 7 or less if its working correctly. You are only at 94.25% rejection.
For comparison I tested mine the other day and had a Tap TDS of 782, post carbon about 750, post RO of 5.8 (99.25% rejection!!!)and RO/DI of less than 0 using a HM Digital COM-100 conductivity meter. Granted I have a hand tested 98+% RO membrane but yours should be better than that.

jbittner · 02/26/2007, 12:37 PM

I am sure it a cheap membrane (six months old at most). When I need to replace I will use a filmtec. I figured as long as post DI I am at 0 all should be ok with my reef. I use a cheap tds meter that probably need to be calibrated. So will the pre-membrane water be fine for drinking and making ice. I think the water tastes great. I was just woried about the tds. I could move it to post RO and run it through an inline carbon filter before splitting it off to the ice machine and drinking spicket. I also worry about water sitting in the storage tank before drinking.

AZDesertRat · 02/26/2007, 01:29 PM

I use RO for drinking and ice maker. It makes CLEAR ice cubes believe it or not! It goes from my RO to a 14G pressure tank andfrom there splits to a drinking water faucet and ice maker in the kitchen through a final taste and odor filter. The other side of the split feeds another RO faucet at my garage laundry sink and my MaxCap DI system for reef water.

jbittner · 02/26/2007, 01:52 PM

So drinking stored RO is fine? I will change my configuration to run my system just like yours. Do you need the final filter before the drinking water?? Do you also filter the water going to the ice machine?

jbittner · 02/26/2007, 02:27 PM

ok. Here is what I did. I put a T coming off the RO. One side is the incoming RO, One leads to the storage tank the other goes into the DI chambers. The other end of the DI runs to the tank and still has a tds of 0. On the line leading into the storage tank I sliced off for the lines that will run to the sink faucet and the ice machine. I get a TDS of 3 coming out of the spicket as just RO (99.14% rejection rate). Do I need a inline filter to the spicket and ice machine?? Is water with a TDS of 3 ok for drinking and ICE. I run a small resturaunt so I want to be sure.

AZDesertRat · 02/26/2007, 02:41 PM

3 from RO only is great. I would add a final taste and odor carbon filter for the drinking and icemaker as RO can have a bland taste without it. This is how lots of soda vending machines are run.

jbittner · 02/26/2007, 03:48 PM

thanks for all your help AZ

02/26/2007, 10:10 AM	#1
jbittner Registered Member Join Date: Feb 2002 Location: Humboldt, NE Posts: 1,014	RO filter ? I just replaced my RO filters and I thought I should do some testing. My results were interesting. I have a 6 stage RO/DI that I have had for a few years. Tap H2O= 348 before RO=338 Post RO=20 Post DI=0 The number that concerns me is the before RO 338. I thought the sediment and carbon would remove more that 10 tds. I use the before RO water for drinking and thought the TDS would be lower. I am also concerned about RO life with so much TDS hitting the membrane.

02/26/2007, 11:44 AM	#2
jbittner Registered Member Join Date: Feb 2002 Location: Humboldt, NE Posts: 1,014	^

02/26/2007, 12:14 PM	#3
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	Prefilters remove sediment or suspended solids (TSS-Total Suspended Solids) not dissolved solids(TDS-Total Dissolved Solids). Carbon blocks remove chlorine and volatile organic chemicals (VOCs). Its the membrane that is the workhorse and removes the dissolved particles that are in the microscopic or even atomic range, much much smaller than suspended solids. How old is the membrane, what brand and model is it and how long did you let the water run before testing the TDS? 20 is not very good at all especially if its a new membrane, it should be about 6 or 7 or less if its working correctly. You are only at 94.25% rejection. For comparison I tested mine the other day and had a Tap TDS of 782, post carbon about 750, post RO of 5.8 (99.25% rejection!!!)and RO/DI of less than 0 using a HM Digital COM-100 conductivity meter. Granted I have a hand tested 98+% RO membrane but yours should be better than that.

02/26/2007, 12:37 PM	#4
jbittner Registered Member Join Date: Feb 2002 Location: Humboldt, NE Posts: 1,014	I am sure it a cheap membrane (six months old at most). When I need to replace I will use a filmtec. I figured as long as post DI I am at 0 all should be ok with my reef. I use a cheap tds meter that probably need to be calibrated. So will the pre-membrane water be fine for drinking and making ice. I think the water tastes great. I was just woried about the tds. I could move it to post RO and run it through an inline carbon filter before splitting it off to the ice machine and drinking spicket. I also worry about water sitting in the storage tank before drinking.

02/26/2007, 01:29 PM	#5
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	I use RO for drinking and ice maker. It makes CLEAR ice cubes believe it or not! It goes from my RO to a 14G pressure tank andfrom there splits to a drinking water faucet and ice maker in the kitchen through a final taste and odor filter. The other side of the split feeds another RO faucet at my garage laundry sink and my MaxCap DI system for reef water.

02/26/2007, 01:52 PM	#6
jbittner Registered Member Join Date: Feb 2002 Location: Humboldt, NE Posts: 1,014	So drinking stored RO is fine? I will change my configuration to run my system just like yours. Do you need the final filter before the drinking water?? Do you also filter the water going to the ice machine?

02/26/2007, 02:27 PM	#7
jbittner Registered Member Join Date: Feb 2002 Location: Humboldt, NE Posts: 1,014	ok. Here is what I did. I put a T coming off the RO. One side is the incoming RO, One leads to the storage tank the other goes into the DI chambers. The other end of the DI runs to the tank and still has a tds of 0. On the line leading into the storage tank I sliced off for the lines that will run to the sink faucet and the ice machine. I get a TDS of 3 coming out of the spicket as just RO (99.14% rejection rate). Do I need a inline filter to the spicket and ice machine?? Is water with a TDS of 3 ok for drinking and ICE. I run a small resturaunt so I want to be sure.

02/26/2007, 02:41 PM	#8
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	3 from RO only is great. I would add a final taste and odor carbon filter for the drinking and icemaker as RO can have a bland taste without it. This is how lots of soda vending machines are run.

02/26/2007, 03:48 PM	#9
jbittner Registered Member Join Date: Feb 2002 Location: Humboldt, NE Posts: 1,014	thanks for all your help AZ