I surgested Zinc earlier, but to my knowledge this only applies when reacting with oxygen. and its not a sacrifical anode in that system, its just a sacrifical metal, because oxidises more readily then steel or aluminium.

Yes

and

Yes so does the rad

Maybe but will it attualy cause a problem? will it attualy be noticeible after the couple of years? So far the answer is no. i dont deny it happens but i dont relly see at as a problem in my case. When i building stuff to sell then it is a problem because there are a differant set of requirements. :dome:

That's a misleading statement. We were discussing the addition of aluminum to an otherwise copper system. In this case, a basic galvanic couple is formed. In any galvanic couple we use the terms "cathode" and "anode" to distinguish the two.

It's like labelling the positive and negative terminals in a circuit.

When you bring in a third metal, your knowledgeable statements about the relationship are true enough. Yes, magnesium trumps aluminum as the anode when all three metals are together.

To say this invalidates what I've said is like poking an earthed wire into a battery-powered circuit. Looks like all I've said about differences in electrical potential is "without knowledge".

Magnesium is used purposefully as an anode against copper/aluminum pairing. Why? Because when copper and aluminum alone are paired, the aluminum anode is sacrificed. So magnesium being way off on the galvanic scale takes the place of aluminum as the sacrificial anode.

Many water supply systems, where copper/brass (and plastic) are the only materials used, employ an aluminum rod as an anode. Its role is purely sacrificial. Without it there would be no anode, and the copper would corrode more rapidly (at the normal rate). Aluminum also trumps steel for the anode of copper, in case glazing on tank walls cracks.

When we're looking at a purely copper system, and we want a sacrificial anode just for the copper, an aluminum plug will serve. In our systems even anodised aluminum will do the trick.

Depends on how you look at it, since chemistry must ultimately deal in electrons. For example, you can call the oxidised (anodised) shell on aluminum a "semiconductor".

I should have been more clear....corrosion will result on unanodized alumnium.

okay, so copper is protected....

what protects your pump/wb from patriculate alumnium matter?

Simple user maintenence. Stang_Man's cap is easy to inspect and clean, unlike the innards of a waterblock. Scour the bottom if/when it appears tarnished. You can do that at the kitchen sink in half a minute, along with the pots. How clean is really up to the user. In any case, I think visible roughening of the surface wouldn't show for many years. Look at grandma's aluminum pans and other hard-use kitchen utensils - are they flaking?

Perhaps;

The point for me is, why the hell should you have to suffer possible problems over 25c of nickel, or perhaps $1 of anodization?

Forgive me for being blunt, but people will pay money for bling; its the simple magpie theory - its shiny, they want it. Nothing will stop them. Don't make them pay by having a substandard design.

Slater - difference is, you're probably using anti-freeze, right? my question earlier, shot down by billA and others, about using anti-freeze is right, in your case, but not when this item is subject to vapourised moisture (as you pointed out, yourself, lol).

Why the HELL should you have to risk your more than probably expensive pump for a 10$ t stopper? makes no sense at all to me.

A water heater tank has a heater in it... will this make it more electrically conductive, which would encourage corrosion? thus requiring an anode?

are they in contact with water and copper?

My grandma has stainless steel or silver-plated nickel utensils. :p

Why risk dirtying a facecloth when you can wrap it in plastic before use? Tarnishing of the cap is not a problem - unless scopic chunks of aluminum oxide are actually crumbling off - the corrosion of the cap guards against corrosion problems for the copper/brass. Maybe that's too much for the average customer to digest.
Good thinking. Galvanic corrosion in electric heaters must be complicated. I can't recall if gas heaters employ an aluminum anode. I guess they could...

However, a basic rule in galvanically corroding pairs is that the cathode will corrode more slowly than by itself. So why not apply that. Add aluminum to an otherwise copper system, the copper is protected.
The tailpipe in her stainless sink is brass, if not the whole drain system. The water flows out of copper pipes, and may even be green from that. She likely soaks aluminum with various metals and solvents... I don't know. We want a real world answer to this question of how much corrosion, and unfortunately only time has the answer.

I am no expert on galvanic corrosion, nor will I claim to be one - but it seems to me that this issue was settled long ago:

I don't see anything really arguable there - you can argue anodes for a boat or a gas fired heater, but that has little bearing on Watercooling in this case

Neither I. But just read off the top of Google, and you'll understand more than most.

Google: galvanic corrosion

And here's a brief explanation I like to believe is correct.
The fellow who posted that learned something since then. That's why he abandoned his statements.
Why? :)

***

What are we trying to accomplish here? If your objective in watercooling is to keep the aluminum cap looking new, then sure coat it or whatever. Good enough. If you think minimising tarnish in a copper waterblock more important, then I suggest sacrificial aluminum, scrubbed off from time to time.

The thing is, we are not dealing with systems in which the copper or brass will corrode. There is not point introducing a metal that will corrode and put stuff into the liquid. There is no poin gunking up blocks, pumps and radiators to have a fancy looking T line cap.

I agree pippin88. Honestly I'm not really concerned about some scarcely perceptible oxide on my copper components. It can't be effecting performance much.

Case in point, that Swiftech block all rainbowed with oxide from brazing. A splash of pickle would have cleaned it up, but apparently the oxide is immaterial, or doesn't effect performance enough to justify a cleaning. So if that's true then surely there's no point trying to slow lesser tarnishing with a sacrificial anode.

the thing is, the caps are anodized and they will not corrode at all now.

unless someone is stupid, and deeply scratches one of the caps, well that then is beyond my control.

bill, yes I understand what your saying, sure it can corode and get nasty I have put a peice of copper and aluminum in a jar for a year and there was no chunks but it did get gross, that was when they were submerged together.

Yes I totally agree, Brass would solve the problem 100% and not cost much more like I have said.

So why am I ignorant now? explain bill:)


Jon