Copper in Distilled Water??

[jcr6479]

Over the past few months, I have been using RO not RO/DI water to top off my aquarium. I can get the RO water from Albertsons for 35 cents per gallon or various car washes for 20 cents per gallon. I just recently invested in a tds meter and the RO water from these sources is measuring 7 ppm. I am currently battling GHA and cyano. I have increased my nutrient export process by adding another fuge and also gfo. I do not have the funds or space right now to invest in an RO/DI unit.

I know that distilled water is pure water in that it is literally only 2 oxygen molecules bonded to 1 hydrogen molecule; however, though research, I have learned that some distilled water can contain copper from the distillation units. Although the bottled distilled water is about 85 cents per gallon, I would prefer to use this for top off instead of the 7 ppm RO water. When I measured the distilled water, the TDS meter read 0.

Can I then assume that there is no copper in it or is it possible that there is copper in but not in an ionic form?

 

[AZDesertRat]

Copper in distillation units is pretty rare anymore. That goes back to the days when they were literally stills.

 

[jcr6479]

So it should be fine to use the distilled water right?

 

[Randy Holmes-Farley]

It may be OK, but without knowing exactly how it was made, I'd be reluctant to make that conclusion.

 

[jcr6479]

So then it would be better to use the 7 ppm RO water than the distilled water from an unknown source?

 

[jcr6479]

Would it be okay if I were to run the distilled water through a polyfilter?

 

[Randy Holmes-Farley]

Not a perfect set of choices, IMO, but I would probably prefer the RO, if you made it yourself. Unless the copper is at the very high end of what anyone sees in tap water, that is likely OK. But store RO may be dispensed through copper piping, and that would be bad, IMO. The allowed levels for copper in drinking water are far higher than are OK for a reef.

That assumes there is no chloramine in the tap water used to make the RO. If there is chloramine, then RO only is a bad choice as there is ammonia in the effluent.