Milli-Q water for water changes?

[abby_n]

Has anyone every used milli-Q water for their tank? I am in college and work at a lab where there are taps with purified water (RO and milli-q) that I could use. It would be much easier than what I am doing now to use this water.

Is it safe as long as the conductivity value is low? Any precautions I should take before doing a full water change with it?

[Flaxon-Waxon]

Is there a way to know the TDS of the water? I don’t know what Milli-Q water is but the Googles tell me is essentially double distilled? Correct me if I’m wrong.

You want 0 TDS for saltwater tanks. That may or may not help you answer this.

[abby_n]

Originally Posted by Flaxon-Waxon

Is there a way to know the TDS of the water? I don’t know what Milli-Q water is but the Googles tell me is essentially double distilled? Correct me if I’m wrong.

You want 0 TDS for saltwater tanks. That may or may not help you answer this.

Okay gotcha. Yeah I have a way to measure the TDS so I can check that next time I go in. If the filtration is working as it should be, the TDS should be 0.

Yeah milli-q water is filtered through multiple mediums that should remove ions, organics, and large particles. So it includes the reverse osmosis process.

[Flaxon-Waxon]

Originally Posted by abby_n

Okay gotcha. Yeah I have a way to measure the TDS so I can check that next time I go in. If the filtration is working as it should be, the TDS should be 0.

Yeah milli-q water is filtered through multiple mediums that should remove ions, organics, and large particles. So it includes the reverse osmosis process.

As long as you’re getting 0 TDS, I’d be confident that it will be just fine

I have an RODI unit that currently brings TDS down to about 2-4 before it goes into the DI resin canister, then comes out 0. Some people even feel ok with 2-4 coming out after the DI resin, but I’m good with 0 personally.

[Sniperhank]

I've never worked with Mili-Q, but the college I went to did it's own that it collected from rain water. What I recall, the TDS of this was really close to 0 if not 0. But that was for a reason I'm sure, but there wasn't a DI resin phase like we run to make that final jump from ~10 to 0.
I would use it if it was being offered up to me. If you are concerned about it, I'm sure there is a TDS meter somewhere in one of the departments that someone will let you use without issue. And if you do so, report the results. Would love to know.

[abby_n]

Originally Posted by Sniperhank

I've never worked with Mili-Q, but the college I went to did it's own that it collected from rain water. What I recall, the TDS of this was really close to 0 if not 0. But that was for a reason I'm sure, but there wasn't a DI resin phase like we run to make that final jump from ~10 to 0.
I would use it if it was being offered up to me. If you are concerned about it, I'm sure there is a TDS meter somewhere in one of the departments that someone will let you use without issue. And if you do so, report the results. Would love to know.

The TDS is 0.562 mg/L. That is low enough right?

[Flaxon-Waxon]

That’s definitely low, and likely won’t yield any issues… I won’t personally do anything above 0, but have heard of folks waiting until their TDS is up to 10-12 before they replace filters on their RODI units. If you’re concerned you can run media like a PolyFilter in conjunction with GFO and that will help keep those small amounts in check. What you don’t want is .5ppm compounded over time and becoming a problem, so do what you can to prevent it from getting any higher.