TDS

Aquamann88 · Apr 17, 2024

With how much TDS can I get away in my RODI water for my saltwater tank?
My TDS is coming out of my system 0ppm now the water is about 2 day old and I tested it again and it reads 30ppm, does anyone have an explanation for that ?

Randy Holmes-Farley · Apr 17, 2024

Channeling through the DI? Bad Ro membrane? High CO2?

lapin · Apr 17, 2024

Is the container clean, sealed ?
You didn’t have saltwater in there before hand?

fishywishy · Apr 17, 2024

There’s probably a little bit of salt leftover in the container

Aquamann88 · Apr 17, 2024

lapin said:
Is the container clean, sealed ?
You didn’t have saltwater in there before hand?

Yes,there could have been saltwater in there before.
Once the bucket is full in seal it off.

Aquamann88 · Apr 17, 2024

Randy Holmes-Farley said:
Channeling through the DI? Bad Ro membrane? High CO2?

Not sure if I have high CO2 I will have to get it tested, that was my first thought that it might be the CO2

Aquamann88 · Apr 17, 2024

Can I still use the RO water with my TDS at 30ppm?

Asm481 · Apr 17, 2024

Aquamann88 said:
Can I still use the RO water with my TDS at 30ppm?

I think we might be confused here. Are you saying the rodi system is now producing water at 30ppm or you filled a container several days ago and tested that water today and found 30ppm? If it's the latter I would save myself the concern and never test it again. I trust the container I keep my water in and pay a lot of attention to what goes into it. Meaning it is only used for my tank so all is good.
Now if my rodi is all of a sudden producing 30ppm after letting it flush at start up I am buying a new membrane and cartridges.

Aquamann88 · Apr 17, 2024

Asm481 said:
I think we might be confused here. Are you saying the rodi system is now producing water at 30ppm or you filled a container several days ago and tested that water today and found 30ppm? If it's the latter I would save myself the concern and never test it again. I trust the container I keep my water in and pay a lot of attention to what goes into it. Meaning it is only used for my tank so all is good.
Now if my rodi is all of a sudden producing 30ppm after letting it flush at start up I am buying a new membrane and cartridges.

It produces 0ppm but if it sits a couple days the TDS is climbing up ,yes I only use it for my saltwater aquarium.

Randy Holmes-Farley · Apr 18, 2024

When it sits, there is something called salt creep where ions slowly equilibrate on both sides of the ro membrane. That’s why it is not best to keep constantly turing an ro/di on and off.

That burst of salt may be making it through the di.

If you then run it longer to flush this out, does the tds drop?

Aquamann88 · Apr 19, 2024

Randy Holmes-Farley said:
When it sits, there is something called salt creep where ions slowly equilibrate on both sides of the ro membrane. That’s why it is not best to keep constantly turing an ro/di on and off.

That burst of salt may be making it through the di.

If you then run it longer to flush this out, does the tds drop?

It is coming out of my RODI system 0 TDS
If it sits in my bucket,for some reason my TDS is climbing.

Randy Holmes-Farley · Apr 19, 2024

Aquamann88 said:
It is coming out of my RODI system 0 TDS
If it sits in my bucket,for some reason my TDS is climbing.

Any sort of salty dust or droplets in the air can do that. Or residual stuff in the bucket. Unlikely but possible is for a little to come from a newish bucket itself.

I would not worry about that.