Brass Fitting on RO storage tank

[SciGuy2]

Randy,

I just installed a RO unit over the weekend. One thing troubles me about the unit - it has a brass nipple on the storage tank. The RO water travels from the storage tank through a small carbon "final filter" and then to a sink dispenser.

Will the RO water pick up copper from the brass nipple to an extent that I should be concerned about using it in my reef tank?

Thanks,
-Lee

[Randy Holmes-Farley]

Lee:

<< Will the RO water pick up copper from the brass nipple to an extent that I should be concerned about using it in my reef tank?>>

It could, yes. Is there any way to replace the nipple?

[SciGuy2]

Randy,

First of all my sincerest apologies. I did a search on the words "brass fitting" this morning and saw that you had answered my question several times before. I looked up "RO" prior to posting and got a zillion or so non-applicable hits. Sorry, I typically do a better job of looking things up prior to asking questions - I guess I was frustrated this time.

The nipple appears to be integral to to tank. Also I noticed that the connections between the separate filter bowls are connected by brass fittings.

I've contacted the manufacturer. We'll see what they have to say.

Thank you,
-Lee

[gregt]

Randy,

Since it's been brought up again....

I'm still not convinced that there could be enough copper from a 1/4" length of exposed brass to RO water to make a difference (Mind you I'm still going to replace it, just in case LOL)

I'm not enough of a chemist to even word my "thoughts" correctly, but I'll give it a shot. After a year, there is no noticable corrosion of the brass valve on my system. Just how much copper could leach from a 1/4" length of pipe before you would notice it? How much copper is actually in a 1/4" section of brass valve, even if the entire thing corroded over the course of 2 or 3 years?

Sorry for rambling, I'm just trying to quantify the problem a little better.

[Randy Holmes-Farley]

Greg:

It seems that "dangerous" copper levels are not easy to quantify. Normal copper levels in seawater are very, very low: on the order of 0.00006 ppm. If toxic levels are 1000x nsw, that's still 0.06 ppm, or darn little. So it may not take much to be a problem.

Check out these discussions where someone apparently did have a problem from a brass fitting in the tank (in RO water may or may not be different):

http://www.reefcentral.net/vbulletin/showthread.php?threadid=53138&highlight=brass

http://www.reefcentral.net/vbulletin/showthread.php?threadid=53238&highlight=brass

[gregt]

I completely understand how brass in SW could corrode quickly enough to cause a serious problem.

I guess I figured that 1/4" of exposed brass to RO would be infintestimal compared with the entire piece submerged in SW.

As I said, I'm switching it out anyway, just talking theory here. I guess I'm just looking for a more quantifiable answer, like "One layer of molecules from 1/4" of brass would add x ppm of copper to the water....". But even if that answer were given, I'd still have the question of how long will it take for RO to corrode one layer of molecules. :D

Let me throw another wrench (hopefully it's not a brass wrench) into the works. How about people keeping reefs and using tap water. Isn't it very likely the water is going through 100's of feet of copper piping?

[Randy Holmes-Farley]

Greg:

"One layer of molecules from 1/4" of brass would add x ppm of copper to the water"

On layer of molecules (about 2 x 10^15/cm2) from 1 cm2 of brass (67% copper) would add 0.00014 mg of copper to whatever amount of water. Let's say that is one liter. Then you have Cu = 0.00014 ppm.

To notice it by eye, how much corrision would be needed? How small of a thing can you see? A tenth of a millimeter? Less?

A tenth of a millimeter contains on the order of a million layers of copper.

<< How about people keeping reefs and using tap water. Isn't it very likely the water is going through 100's of feet of copper piping?>>

Yes, people who use tap water run that risk.

It is my expectation that copper is far less toxic ion our tanks than it is in seawater due to the organic complexation that takes place. As far as I know, however, this has not been demonstrated specifically for reef tanks. It is one way to reconcile the reported toxicity (e.g., Ron's assertions) with the fact that copper is apparently present in many tanks at substantial levels.

[SciGuy2]

Randy,

Just out of curiousity, would a DI module added after the all of the brass fittings efectively pull out the copper ions that might be introduced by the plumbing?

Also, since I was planning on drinking the water are the DI resins commonly sold with aquarium grade DI add-on modules food safe?

Thanks again,
-Lee

[gregt]

SciGuy,

Drinking DI water can be detrimental to your health due to the lack of electrolytes. It can actually wash needed minerals from your system. A little here and there is fine, but if you drink a lot of it, you can experience problems. DI water is like the "anti-sports drink". Take your drinking water from the filter before the DI cartridge.

[Randy Holmes-Farley]

Lee:

Yes, an added DI would take out the copper from DI water.

I wouldn't drink water from a TWP cartridge. The quality controls for hobby products don't impress me enough to want to drink from them.

IMO, it's no problem to drink DI water as long as you are also eating and drinking other things. I don't buy the minerals argument. If so, then one should argue that it is important to have a bunch of individual ions in drinking water at some minimum concentrations, and I've never heard such a claim.