water question...001 ro/di water ok?

petere1989 · 01/05/2013, 10:19 AM

I have a Ro/Di system from bulkreefsupply and I had to order new Di resin because mine is brown. The tds meter is reading 001. I just got a new tank and am filling it up, is that water ok to use since its off just a bit? the new resin is coming tuesday.

dirtycontour · 01/05/2013, 10:26 AM

001 is not terrible, but I'd wait for the new resin before filling up. We spend alot of our time trying to remove unwanted stuff from our tanks, why start off on the wrong foot? Just my opinion.

disc1 · 01/05/2013, 10:40 AM

TDS can't tell you anything about the suitability of water for your tank. All that number means is that your di resin is exhausted and there for something is making it past the filter.

dirtycontour · 01/05/2013, 10:43 AM

Quote:

Originally Posted by disc1

TDS can't tell you anything about the suitability of water for your tank. All that number means is that your di resin is exhausted and there for something is making it past the filter.

Sorry, I'm not following. If something is making it past the filter, wouldn't that tell you it's not suitable for the tank?

disc1 · 01/05/2013, 11:28 AM

Not necessarily. It depends on what it is. You don't know so you have to assume it isn't safe. But all TDS told you was that the filter wasn't up to snuff.

For an example, makeup water with 300ppm sodium chloride would read 300ppm on a TDS meter but would be totally usable in your tank.

Water with 100ppb copper sulfate would read zero on your TDS meter but would nuke your tank.

The TDS can't tell you what is in the water so it can't tell you if it is safe or not. It just tells you that the filter is working or not. A working filter produces zero TDS. A working filter produces water that is safe to use.

A filter producing more TDS than zero is not working properly. Whether or not that water is safe is a complete unknown. It might be or might not be. It is a gamble that most prefer not to take.

sleepydoc · 01/05/2013, 12:21 PM

TDI tells you there is something dissolved in the water, not what. It could be sodium, copper, etc. As DI resin depletes there is a risk that it will essentially become an exchange resin - dropping off ions that have previously been adsorbed out of the water will swap for ions that are more adherent to the resin.

For example - say the water coming off the RO membrane has a TDI of 10. 5 of those ions are Cu and 5 are Na. With fresh resin everything gets adsorbed. With resin that is depleted, if Na is more strongly held by the resin than Cu, as the RO water passes through, some of the Cu gets displaced by the Na. The net TDS change is 0 with this, but the effect on the water quality is not.

I don't know what the relative strength of ion adherence is for DI resin, or if it is known, but because of this risk it's recommended to replace your resin as soon as the TDS starts to climb. Perhaps David can elaborate more.

As far as the color change, remember that the color is an indicator. It's meant to represent how much of the resin has been depleted but may not be accurate. High dissolved CO2 (and perhaps other factors) can cause the color to change before the resin is truly depleted. My resin changes color within 2 months, but the TDS remains at 0 for another 6-8 months after that, so for me, the color change is not an accurate indicator of resin life.

01/05/2013, 10:19 AM	#1
petere1989 Registered Member Join Date: Sep 2012 Location: Peoria, Illinois Posts: 949	water question...001 ro/di water ok? I have a Ro/Di system from bulkreefsupply and I had to order new Di resin because mine is brown. The tds meter is reading 001. I just got a new tank and am filling it up, is that water ok to use since its off just a bit? the new resin is coming tuesday.

01/05/2013, 10:40 AM	#3
disc1 -RT * ln(k) Join Date: Sep 2010 Location: Little Rock Posts: 9,705	TDS can't tell you anything about the suitability of water for your tank. All that number means is that your di resin is exhausted and there for something is making it past the filter. __________________ David Current Tank: Undergoing reconstruction...

01/05/2013, 11:28 AM	#5
disc1 -RT * ln(k) Join Date: Sep 2010 Location: Little Rock Posts: 9,705	Not necessarily. It depends on what it is. You don't know so you have to assume it isn't safe. But all TDS told you was that the filter wasn't up to snuff. For an example, makeup water with 300ppm sodium chloride would read 300ppm on a TDS meter but would be totally usable in your tank. Water with 100ppb copper sulfate would read zero on your TDS meter but would nuke your tank. The TDS can't tell you what is in the water so it can't tell you if it is safe or not. It just tells you that the filter is working or not. A working filter produces zero TDS. A working filter produces water that is safe to use. A filter producing more TDS than zero is not working properly. Whether or not that water is safe is a complete unknown. It might be or might not be. It is a gamble that most prefer not to take. __________________ David Current Tank: Undergoing reconstruction...

01/05/2013, 12:21 PM	#6
sleepydoc Registered Member Join Date: Oct 2011 Location: Minneapolis, MN Posts: 3,907	TDI tells you there is something dissolved in the water, not what. It could be sodium, copper, etc. As DI resin depletes there is a risk that it will essentially become an exchange resin - dropping off ions that have previously been adsorbed out of the water will swap for ions that are more adherent to the resin. For example - say the water coming off the RO membrane has a TDI of 10. 5 of those ions are Cu and 5 are Na. With fresh resin everything gets adsorbed. With resin that is depleted, if Na is more strongly held by the resin than Cu, as the RO water passes through, some of the Cu gets displaced by the Na. The net TDS change is 0 with this, but the effect on the water quality is not. I don't know what the relative strength of ion adherence is for DI resin, or if it is known, but because of this risk it's recommended to replace your resin as soon as the TDS starts to climb. Perhaps David can elaborate more. As far as the color change, remember that the color is an indicator. It's meant to represent how much of the resin has been depleted but may not be accurate. High dissolved CO2 (and perhaps other factors) can cause the color to change before the resin is truly depleted. My resin changes color within 2 months, but the TDS remains at 0 for another 6-8 months after that, so for me, the color change is not an accurate indicator of resin life. __________________ ~~~~~~~~~~~~~~~~~~~~~ 120 gallon, coast to coast overflow w/beananimal overflow. Waveline DC 10000 II return pump, 40 gal sump, Octopus XS200 skimmer, T5 lighting

01/05/2013, 10:26 AM	#2
dirtycontour Registered Member Join Date: Oct 2012 Location: NJ Posts: 256	001 is not terrible, but I'd wait for the new resin before filling up. We spend alot of our time trying to remove unwanted stuff from our tanks, why start off on the wrong foot? Just my opinion.