Copper in distilled water

Randy Holmes-Farley

Reef Chemist
Premium Member
I know many folks have used it OK, but I just want to keep pointing out to folks that copper is a contaminant in distilled water, and can be present at pretty high concentrations.

I personally would avoid distilled water for regular use out of concern for copper. In some cases it is OK, but in others it may not be.

The copper comes from the alloys used in the condensers.

This study in 1996 shows that copper from distilled water (25-30 ug/L = ppb) is significantly higher than my tank (by about a factor of 2-3), and I wouldn't want to be using it.

https://www.google.com/url?sa=t&rct...hd29S1kqrQxw0VRUZ2egxkQ&bvm=bv.70138588,d.aWw

See page 203, table 53
 
I appreciate the side of caution, however, I suspect much has improved in water bottling in the nearly 20 years since that report. In my experience I have exclusively used bottled demineralized water without any issues. I've also used multiple store brands. For me, with a 16 gal nano tank, it is comparable to using an RO unit, I just pick it up when grocery shopping. I do a 25% water change every two to three weeks at a cost of $4, plus about $1/week for top off, that's just over $100/year. Given the cost of an RO unit and periodic filters changes, payback may take a couple years. I'm content with my routine and see no apparent copper effects from bottled demineralized water.
 
I'm glad it seems to be working for you. :)

For any reef, however, even my own, I'd be hard pressed to say it could not be better if I did "X" differently. :)
 
I wondered about that on the other thread recently. I know you can get glass distilled but I don't know where. So the stuff at the supermarket comes from copper condensers?
 
I wondered about that on the other thread recently. I know you can get glass distilled but I don't know where. So the stuff at the supermarket comes from copper condensers?

I use nothing but cheap distilled water from the grocery store and my SPS and LPS are flourishing, no copper. This is my experience only.
 
So the stuff at the supermarket comes from copper condensers?

It is unlikely but possible to come from a copper condenser, but if it did, the values would be higher (I have data for that in some ancient thread, but not on hand). The data above is for corrosion resistant alloys that have some copper in them.

I use nothing but cheap distilled water from the grocery store and my SPS and LPS are flourishing, no copper.

I don't doubt the former, but how do you know the copper level in the distilled water or the tank?
 
So the stuff at the supermarket comes from copper condensers?

It is unlikely but possible to come from a copper condenser, but if it did, the values would be higher (I have data for that in some ancient thread, but not on hand). The data above is for corrosion resistant alloys that have some copper in them.

I use nothing but cheap distilled water from the grocery store and my SPS and LPS are flourishing, no copper.

I don't doubt the former, but how do you know the copper level in the distilled water or the tank?
Great point, perhaps i overstated it. I can only deduce no copper from the robust sustained coral growth and good fish health. I have never tested for it nor do I have the capability. Again, this is just my experience here with multiple brands of demin water. I would assume if copper was present in any harmful quantities it would become evident in over a year of continued use.
 
I know many folks have used it OK, but I just want to keep pointing out to folks that copper is a contaminant in distilled water, and can be present at pretty high concentrations.

I personally would avoid distilled water for regular use out of concern for copper. In some cases it is OK, but in others it may not be.

The copper comes from the alloys used in the condensers.

This study in 1996 shows that copper from distilled water (25-30 ug/L = ppb) is significantly higher than my tank (by about a factor of 2-3), and I wouldn't want to be using it.

https://www.google.com/url?sa=t&rct...hd29S1kqrQxw0VRUZ2egxkQ&bvm=bv.70138588,d.aWw

See page 203, table 53


This makes a lot of sense for a copper condenser setup, however when I started reefing I used glass double distilled water. I think using a glass condenser mitigates a lot of the issues with copper and the tank always did great. Now I just use RO/DI though.
 
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