What should RO tds be?

whirley · 08/28/2006, 10:20 PM

What should RO water's TDS be? I'm registering 40 ppm, but I just installed the system tonight, so I assume that I have to run it a little longer.

I do have horrible water.

Thanks!

AZDesertRat · 08/28/2006, 10:27 PM

Without knowing your tap water TDS and what membrane you have that question can't be answered accurately.
If you have a true RO 75 GPD membrane and your membrane is new you should be seeing a 96 to 98% or higher reduction from tap water. If you have a Dow Filmtec 100 GPD membrane you should be seeing about 90% rejection.
It also takes at least 5 gallons or more for a new membrane to settle in. Vendors recommend you toss the first 5 to 10 gallons of RO.
If you have DI also, remove the DI cartridge during the initial flushing process so you don't shorten its life.

orlenz · 08/28/2006, 10:27 PM

on my system input is usually around 260, after the sediment filter and the carbon blocks and RO it comes out at 6, then It goes through two 10" DI filters and comes out zero. you want it at zero or close to it.
if your getting 40 you could upgrade by adding a full size DI or two. or possibly get a better membrane what membrane are you using?

whirley · 08/29/2006, 01:41 PM

Hrmm...well, I'm getting 300 before the RO unit, 35-40 after.
After my DI, I get 5-6....

Hrmm...looks like I'll have to add another DI, eh?

thanks for the help!

whirley

javajaws · 08/29/2006, 02:15 PM

What brand RO/DI unit do you have and how many GPD is it rated at?

wannabefishguru · 08/29/2006, 03:25 PM

this is a hijack, everyone get down

i know you can drink RO water, but can you drink RO/DI water?

oh if you have a lower gpd does this mean more water contact in the units?

AZDesertRat · 08/29/2006, 05:00 PM

Whirley you don't need a second DI, you need a new RO membrane. I am assuming from your readings it is either completely worn out or it started life as a 90% rejection rate 100 GPD nanofilter and not a true 98% rejection rate RO membrane. A new RO membrane will get you down to about 6 ppm TDS with RO only and DI resin should last you quite a while if it is a decent DI filter and not a horizontal tube with some beads floating around in it.

Yes you can drink RO/DI water with no proven ill effects. You really don't want to though as it tastes very bland and is expensive to produce. Lower GPD just means there is less TFC membrane material wound around the core so you have less surface area to pass water through. It has nothing to do with contact time.

outy · 08/29/2006, 05:49 PM

azdesertrat is rite on the money

the wife drinks the water after the carbon filters, taste better and no life taken off ro/di

AZDesertRat · 08/29/2006, 06:02 PM

I drink RO water which has been passed through an additional carbon filter and its tastes fine.

Raibaru · 08/29/2006, 09:41 PM

Well I feel like an idiot... I just filled my aquarium with the RO/DI water and tested my tap and such. This TDS meter I got from Purely was reading 005. the water that came out as 000.

It has one button (and no manual) so I figured I did everything right. Put some in cup, push button, dip in water, sit a sec, read. To think you guys have numbers in the hundreds I obviously did something wrong.

Could someone explain it to me?

AZDesertRat · 08/29/2006, 09:59 PM

5 sounds a little fishy? Even in the Atlanta area which has some of the best water I have ever heard of its a little higher than that. Where are you located and can you contact your local water utiity and ask for their lates twater quality report? It may even be online if its a very large utility.

Raibaru · 08/29/2006, 10:05 PM

I live in Baltimore, Maryland and I have no idea who we get our water from unless it is just the city of baltimore.

The meter I'm using is this

Only has one button, but no manual came with it.

Now I'm worried because the Ro/Di unit came with 2 packs of buffer solution, but I was told (not by purely) that these are additives to the water and not something I add to the unit itself...

I really hope I didn't just make 36g of really expensive tap water.

hodsgod · 08/29/2006, 10:14 PM

I have RO only, my tap water is 100 TDS, my Brita filter is 50 TDS and my RO unit is around 5/6 TDS.

I am quite happy with that, since I bought it I have no algae.

AZDesertRat · 08/29/2006, 10:24 PM

I am guessing what they gave you is a calibration solution for the TDS meter? What is your tap water TDS, RO only TDS and RO/DI TDS? The meter should be precalibrated but you could use one of the packets and check it to be sure.

Raibaru · 08/29/2006, 10:26 PM

Well when I used the meter my tap TDS was 005. When it went all the way through the RO/DI unit (with the DI) it came out and read 000.

How do I use the solutions to calibrate the meter? The solutions are labeled Hanna Instruments pH 7.01 buffer solution and the other is pH10.01 buffer solution.

AZDesertRat · 08/29/2006, 10:33 PM

Those won't do you any good they are for calibrating a pH meter not a TDS meter.
Wow a tap water TDS of 5 is amazing. I would check with oter reefers in your area to see what they are getting. It just sounds a little suspicious to me, a TDS of 5 would be very agressive water and would eat copper pipes and solder like crazy.

Raibaru · 08/29/2006, 10:36 PM

Alright, well I just filled the sink with water and put the meter in and got 143. I then filled a small cup up of my salt water and got an error? lol... this is getting fun now.

With my other meter I'm getting a pH of 8 and a temp of 74.

Don't be alarmed by those numbers though. I haven't put the heater in and the salt still isn't entirely dissolved.

AZDesertRat · 08/29/2006, 10:40 PM

Don't test saltwater with the TDS meter. It could contaminate the probe and ruin it. It can easily be way over the meters range, in the thousands more than likely.

Raibaru · 08/29/2006, 10:42 PM

Alright, just ran another cup of water through the RO/DI unit. It came back with a reading of 47.

I tested my bottled spring water and came back with 7.

Are these numbers any more realistic?

AZDesertRat · 08/29/2006, 10:45 PM

Sounding better. Make sure you rinse the meter with DI water after each use and before putting it away to keep the probes clean. I have a dedicated glass that is used only for TDS sampling and is always squeaky clean with no soaps or residues in it so I get consistent readings.

Raibaru · 08/29/2006, 10:48 PM

Phew, thanks a ton AZDesertRat, I'm going nuts with everything now that I'm getting close to upgrading my title from Water Wrestler to Rock Wrangler. Cant wait to see how much goes wrong when I get ready to upgrade my title to Fish Aficionado.

I also promise to not make any bad jokes in the future...

AZDesertRat · 08/29/2006, 10:55 PM

Its all about having fun! It helps if you do things right the first time too as it allows you more time to enjoy and less time on maintenance or redoing what you have already attempted 6 or 7 times already (not that I ahve ever done that!).

08/28/2006, 10:20 PM	#1
whirley Registered Member Join Date: Jul 2001 Location: Granger Indiana Posts: 1,264	What should RO tds be? What should RO water's TDS be? I'm registering 40 ppm, but I just installed the system tonight, so I assume that I have to run it a little longer. I do have horrible water. Thanks! __________________ whirley whirley@yahoo.com he said SKILTER ---> HEHEHEHHAHHWoo....Thanks, I needed a laugh. Current Tank Info: Infinite

08/29/2006, 01:41 PM	#4
whirley Registered Member Join Date: Jul 2001 Location: Granger Indiana Posts: 1,264	Hrmm...well, I'm getting 300 before the RO unit, 35-40 after. After my DI, I get 5-6.... Hrmm...looks like I'll have to add another DI, eh? thanks for the help! whirley __________________ whirley whirley@yahoo.com he said SKILTER ---> HEHEHEHHAHHWoo....Thanks, I needed a laugh. Current Tank Info: Infinite

08/29/2006, 02:15 PM	#5
javajaws Premium Member Join Date: Feb 2004 Location: Round Rock, TX Posts: 1,620	What brand RO/DI unit do you have and how many GPD is it rated at? __________________ Everyone has an opinion. Accept the fact now that someone isn't going to like yours sooner or later. Current Tank Info: 110g in-wall, ATI 8x54w T5, 2xMP40es, SRO XP-2000i, 2-part Ca/Alk, Apex controlled

08/28/2006, 10:27 PM	#2
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	Without knowing your tap water TDS and what membrane you have that question can't be answered accurately. If you have a true RO 75 GPD membrane and your membrane is new you should be seeing a 96 to 98% or higher reduction from tap water. If you have a Dow Filmtec 100 GPD membrane you should be seeing about 90% rejection. It also takes at least 5 gallons or more for a new membrane to settle in. Vendors recommend you toss the first 5 to 10 gallons of RO. If you have DI also, remove the DI cartridge during the initial flushing process so you don't shorten its life.

08/28/2006, 10:27 PM	#3
orlenz Awaiting Email Confirmation Join Date: Feb 2005 Location: California Posts: 1,648	on my system input is usually around 260, after the sediment filter and the carbon blocks and RO it comes out at 6, then It goes through two 10" DI filters and comes out zero. you want it at zero or close to it. if your getting 40 you could upgrade by adding a full size DI or two. or possibly get a better membrane what membrane are you using?

08/29/2006, 03:25 PM	#6
wannabefishguru Registered Member Join Date: Aug 2006 Posts: 84	this is a hijack, everyone get down i know you can drink RO water, but can you drink RO/DI water? oh if you have a lower gpd does this mean more water contact in the units?

08/29/2006, 05:00 PM	#7
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	Whirley you don't need a second DI, you need a new RO membrane. I am assuming from your readings it is either completely worn out or it started life as a 90% rejection rate 100 GPD nanofilter and not a true 98% rejection rate RO membrane. A new RO membrane will get you down to about 6 ppm TDS with RO only and DI resin should last you quite a while if it is a decent DI filter and not a horizontal tube with some beads floating around in it. Yes you can drink RO/DI water with no proven ill effects. You really don't want to though as it tastes very bland and is expensive to produce. Lower GPD just means there is less TFC membrane material wound around the core so you have less surface area to pass water through. It has nothing to do with contact time.

08/29/2006, 05:49 PM	#8
outy Moved On Join Date: Oct 2004 Location: auburn CA Posts: 4,021	azdesertrat is rite on the money the wife drinks the water after the carbon filters, taste better and no life taken off ro/di

08/29/2006, 06:02 PM	#9
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	I drink RO water which has been passed through an additional carbon filter and its tastes fine.

08/29/2006, 09:41 PM	#10
Raibaru Registered Member Join Date: Aug 2006 Location: Maryland Posts: 979	Well I feel like an idiot... I just filled my aquarium with the RO/DI water and tested my tap and such. This TDS meter I got from Purely was reading 005. the water that came out as 000. It has one button (and no manual) so I figured I did everything right. Put some in cup, push button, dip in water, sit a sec, read. To think you guys have numbers in the hundreds I obviously did something wrong. Could someone explain it to me?

08/29/2006, 09:59 PM	#11
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	5 sounds a little fishy? Even in the Atlanta area which has some of the best water I have ever heard of its a little higher than that. Where are you located and can you contact your local water utiity and ask for their lates twater quality report? It may even be online if its a very large utility.

08/29/2006, 10:05 PM	#12
Raibaru Registered Member Join Date: Aug 2006 Location: Maryland Posts: 979	I live in Baltimore, Maryland and I have no idea who we get our water from unless it is just the city of baltimore. The meter I'm using is this Only has one button, but no manual came with it. Now I'm worried because the Ro/Di unit came with 2 packs of buffer solution, but I was told (not by purely) that these are additives to the water and not something I add to the unit itself... I really hope I didn't just make 36g of really expensive tap water.

08/29/2006, 10:14 PM	#13
hodsgod Registered Member Join Date: Jan 2006 Location: Yokohama, Japan Posts: 155	I have RO only, my tap water is 100 TDS, my Brita filter is 50 TDS and my RO unit is around 5/6 TDS. I am quite happy with that, since I bought it I have no algae.

08/29/2006, 10:24 PM	#14
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	I am guessing what they gave you is a calibration solution for the TDS meter? What is your tap water TDS, RO only TDS and RO/DI TDS? The meter should be precalibrated but you could use one of the packets and check it to be sure.

08/29/2006, 10:26 PM	#15
Raibaru Registered Member Join Date: Aug 2006 Location: Maryland Posts: 979	Well when I used the meter my tap TDS was 005. When it went all the way through the RO/DI unit (with the DI) it came out and read 000. How do I use the solutions to calibrate the meter? The solutions are labeled Hanna Instruments pH 7.01 buffer solution and the other is pH10.01 buffer solution.

08/29/2006, 10:33 PM	#16
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	Those won't do you any good they are for calibrating a pH meter not a TDS meter. Wow a tap water TDS of 5 is amazing. I would check with oter reefers in your area to see what they are getting. It just sounds a little suspicious to me, a TDS of 5 would be very agressive water and would eat copper pipes and solder like crazy.

08/29/2006, 10:36 PM	#17
Raibaru Registered Member Join Date: Aug 2006 Location: Maryland Posts: 979	Alright, well I just filled the sink with water and put the meter in and got 143. I then filled a small cup up of my salt water and got an error? lol... this is getting fun now. With my other meter I'm getting a pH of 8 and a temp of 74. Don't be alarmed by those numbers though. I haven't put the heater in and the salt still isn't entirely dissolved.

08/29/2006, 10:40 PM	#18
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	Don't test saltwater with the TDS meter. It could contaminate the probe and ruin it. It can easily be way over the meters range, in the thousands more than likely.

08/29/2006, 10:42 PM	#19
Raibaru Registered Member Join Date: Aug 2006 Location: Maryland Posts: 979	Alright, just ran another cup of water through the RO/DI unit. It came back with a reading of 47. I tested my bottled spring water and came back with 7. Are these numbers any more realistic?

08/29/2006, 10:45 PM	#20
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	Sounding better. Make sure you rinse the meter with DI water after each use and before putting it away to keep the probes clean. I have a dedicated glass that is used only for TDS sampling and is always squeaky clean with no soaps or residues in it so I get consistent readings.

08/29/2006, 10:48 PM	#21
Raibaru Registered Member Join Date: Aug 2006 Location: Maryland Posts: 979	Phew, thanks a ton AZDesertRat, I'm going nuts with everything now that I'm getting close to upgrading my title from Water Wrestler to Rock Wrangler. Cant wait to see how much goes wrong when I get ready to upgrade my title to Fish Aficionado. I also promise to not make any bad jokes in the future...

08/29/2006, 10:55 PM	#22
AZDesertRat Moved On Join Date: Jan 2002 Location: NW Phoenix Posts: 16,621	Its all about having fun! It helps if you do things right the first time too as it allows you more time to enjoy and less time on maintenance or redoing what you have already attempted 6 or 7 times already (not that I ahve ever done that!).