How much TDS do you allow?

[Learning Man]

I think if you follow Randy’s link he does explain it.

 

[Randy Holmes-Farley]

Yes, it is detailed there.

Take, for example, your water supply using chloramine. Mine does. Ammonia passes the RO pretty easily, so there is quite a bit of ammonia accumulating in the DI. None gets through before depletion, but it is holding a lot of ammonia.

Then once all of the binding sites in the DI get depleted, the same number of ions coming into the DI in will be coming out, but they aren't necessarily the same ones. The DI holds differently ions differently, and ammonium and silicate happen to be held weakly, so they can easily be displaced by incoming sodium,. chloride, etc.

So say that 5 ppm TDS into the DI consists of 0.05 ppm ammonia, 0.05 ppm silicate, and 4.9 ppm of sodium, chloride, etc

The outflow might then contain 5 ppm that is mostly ammonium and silicate, with little sodium and chloride.

So that 5 ppm coming in to the DI would have been OK, but that 5 ppm coming out might be a lot worse, and might even be worse than the tap water even before the RO.

 

[steelcaveman]

Interesting. I may need to get an inline TDS. I've been measuring the water in big bucket. I have found that the longer the water sits, the higher the TDS reading in the bucket, so I try to use the water as quickly as possible. I have a feeling that the rubbermaid maid leach a bit.

 

[Randy Holmes-Farley]

Yes, inline is best for RO/DI monitoring. Water readily picks up CO2 from the air, salt spray, etc and the TDS rises even if the container is perfect.

 

[savethereef]

i change mine when my DI hits over 1-2 TDS which is about every 3-4 months. As for my regular filters i change them about every year. My regular RO i get a TDS of 7

I love my Air Water and iCe

 

[spleify]

As soon as I see 1 i change things

 

[sabien]

Just tested TDS after buying a used RODI with newly replaced filters (yeah right!).

TDS tap water is 51. TDS out of RODI is 71. I hate dishonest people.

If you don't change them they will leach back out as Randy mentioned.

 

[Randy Holmes-Farley]

Did you run it a bit first?

 

[bkcjames]

I dont allow anything over 0...

 

[cuse1]

change mine as well at 1

 

[Pcrain]

i have ran mine up to 20 tds with no ill results I test everything once a month and have never had a detectable ammonia count in my tank.. i cant afford to change my ro/di every 4-6 months that makes it cheaper to go to the store and actually purchase the water then to run the RO/DI .

 

[csdavis]

I too change mine at 5 which usually works out to be every 6 months.

 

[preef]

I replace at 1 or 2. If you wait too long, the TDS of the DI output can be higher than the DI input/RO output. It can climb pretty quickly once the resin is depleted so you need to keep an eye on it.

One time I got lazy and wasn't checking the TDS. Started seeing cyano in the tank so I checked and the TDS of the DI was around 20.

 

[Curtie44]

Just curious, how often do all of you guys do a backflush on your RO membrane?

 

[t00lfan]

I need to backflush. I have to disconnect mine from the sink everytime. Do any of you guys empty the water out or leave the water sit in the unit?

 

[NYC/NJREEFS]

TDS Allowed from RO/DI

TDS Allowed from RO/DI

I recently replaced mine after a full year of use. I am fighting my green algae problem so I decided to replace them all including the di resin. I am reading straight zeros from my Di output. I think thats what we should aim for to prevent problems in the tank, right? Good luck and happy reefing.

 

[Reefer Brian]

I need to backflush. I have to disconnect mine from the sink everytime. Do any of you guys empty the water out or leave the water sit in the unit?

If you have to disconnect it after each use, do not drain it completley, allow it to remain full of water to keep all the filters wet.