4-5 on TDS meter is this ok?

[jjschwi]

after going through my RODI filter the water has a TDS of 4-5
is this good enough? Before going through filter its about 378.
The filters look like they are still ok.

[Saltz Creep]

That's still a 98-99 percent reduction which is expected. It's just that you tap water is pretty high in TDS. Mine is only 167ppm.

[AZDesertRat]

You need to check a couple of things to determine if your filters are good. You know your raw water tds already. Next you need to test the effluent of the RO only before DI. And you already havethe post DI readings.
If you have a 100 GPD membrane you should be getting about 90% removal with the membrane alone and no DI. If its a 25,50 or 75 GPD RO membrane you should be seeing 98% removal with the RO only.
I would bet you DI resin is exhausted and needs replacing but by getting all the above info it wil tel you where to look.
My raw water is 650 to 800 TDS, post 75GPD membrane is about 13 TDS and DI stays at 0 for between 150 to 200 gallons before I start seeing it creep up to 3 or so when I replace it.
As far as is it good enough, some bad things tend to release themselves back into the effluent water after a point so it is best to replace the DI resin once you get to 3 to 5 or so.

[jjschwi]

thanks, the last stage or DI is the one that lays flat on the top right? I have another filter in standby, I think mine is a 75 gph
its an Oceanic. I dont have any idea of how much water I have ran through it. I have noticed my pressure reading fall of as well, I think when it was new I got close to 70 on my pressure meter, but now I am around 60, I wonder if that is an indication that the DI is tapped out as well.

[AZDesertRat]

I use my unit for drinking water and ice as well so I change the prefilter and 2 carbon blocks every six months. My membranes last about 16 to 20 months. And like I already said DI lasts about 150 to 200 gallons. I have a vertical refillable DI cartridge which is the best way to go since bulk resin refills are less than $9 each. Much cheaper than the smaller horizontal filters, but yes that is probably the DI on top although some units have a post carbon filter that is very similar in size.

[integlikewhoa]

The DI filter dont have to be last and it dont have to be on top either. You might want to post pics or find out first.

[jjschwi]

well there are three of them that are verticle and there huge.
big round ones that are clear plexiglass around them and then,
the little white one on the top, lying horizontal.

This is my filter

http://www.aquaticreefsystems.com/Reverse_Osmosis_4Stage.htm

[antony1103]

Yhe DI is most likely the canister on the left. The on on top it the membrane hosing.

[socalreefer73]

it's winter.. ambient temperature/incoming water temp affects the operation or your RO/DI....

Well, it's winter in cali.. : P

my tap water is about 230 and I got a 1 tds last time I checked mine.. I would say 3 or 4 is still excellent...

DI will be the last stage, if your device is equipped with one... just follow the tubing...

[AZDesertRat]

3 or 4 is not excellent after a DI. After a 98% efficient RO membrane with a raw water TDS of 350-400 that is excellent. What it is probably telling you is the DI isn't doing squat. A 75 GPD RO should be producing an effluent TDS of no more than 6 to 8 even without a DI post filter. Check your post RO before the DI and you will probably see just that. If its higher than 15 to 20 the RO membrane needs replaced. Talk with the guys at Aquatic Reef Systems, they are some of the best in the business and won't steer you wrong.

[Randy Holmes-Farley]

Here's my recommendations about the TDS of purified water:

from:

What is TDS?
http://www.reefkeeping.com/issues/2004-04/rhf/feature/index.htm

"7. If you are using a TDS or conductivity meter to monitor the performance of an RO membrane, then the measured value should drop by at least a factor of 10 from the starting tap water. So, for example, if the tap water reads 231 ppm, then the RO water should be less than 23 ppm. In many cases, it will drop much more than that. Less of a drop than a factor of 10 indicates a problem with the RO membrane.

8. If you are using a TDS or conductivity meter to monitor the performance of an RO/DI system, then the measured value should drop to near zero. Maybe 0-1 ppm. Higher values indicate that something is not functioning properly, or that the DI resin is becoming saturated and needs replacement. However, that does not necessarily mean that 2 ppm water is not OK to use. But beware that it may begin to rise fairly sharply when the resin becomes saturated. Do not agonize over 1 ppm vs. zero ppm. While pure water has a TDS well below 1 ppm, uncertainties from carbon dioxide in the air (which gets into the water and ionizes to provide some conductivity) and the TDS meter itself may yield results of 1 or 2 ppm even from pure water. "

[diverrad]

WOW you guys have high TDS in your tap mine is only 48 guess NYC has good water

[PRC]

Ummm, from the website that you posted there's a link to a technical diagram of the filter http://www.aquaticreefsystems.com/oceanusdiagram.htm . The horizontal canister (as it is in any RODI unit I've ever seen) is the RO membrane. The DI canister is the vertical one on the left.
As AZDesertRat mentioned, I replace the DI resin when I start seeing pretty much any TDS reading at all. If I let mine go much past 3ppm it tends to jump up pretty quickly as the resin releases impurities back into the water.

[mike89t]

My TDS out of the Tap measures 1100! :eek2:

My Typhoon III RO/DI takes it down to ZERO!

[NHMarine]

Originally posted by mike89t
My TDS out of the Tap measures 1100! :eek2:

My Typhoon III RO/DI takes it down to ZERO!


WOW!!...Do you happen to live near a Nuclear Power Plant?:lol:

My well water runs 65, with RO/DI it's 0

[AZDesertRat]

No we get surface water which is supplied by the Colorado River via aquaduct and from the Salt River which you can tell by its name is high in TDS and other things. Treatment Plants in Arizona don't do any softening so water is just plain old hard.