As you may already know,aluminum prices have crashed very hard.
I can buy 4" round 6160 aluminum for only $6.16 per 1-1/8" but it would need to be anodized for use in chlorinated swimming pools,which I will be submerging into an Olympic size public pool.
I can also buy 4" round 360 brass but it is $36.00 per 1-1/8" and is far superior to anodized aluminum for corrosion resistance.It is three times the weight but not that much.I like the idea of easier repair with brazing brass and the longivity.
I'm not comparing this with plastic,I'm using metal, and I am machining the end plugs myself, so what are your opinions.
I don't think you need to anodize aluminium when using it in chlorinated water.
Like lead, it forms an continuous oxidic layer when it is exposed to oxygen (no matter if from air or solved in water).
Anodization is just an expanding of this layer by using electricity.
As long as there is no voltage on the part, the complete oxidation would take much longer than a model's life.
You can use saltwater-proof aluminium used for building ships, if you want to be sure but it will be more expensive.
I have read that the anodization thickens the parts, not much, but it can be a problem if you have small part or tight fits.
"Zwei Dinge sind unendlich: Das Universum und die menschliche Dummheit. Aber bei dem Universum bin ich mir noch nicht ganz sicher" Albert Einstein
I am in the swimming pool industry (www.indeksolar.com) and have seen the corrosiveness of public swimming pool water chemistry.The problem with municipal swimming pools is that they cannot afford the high cost of water metering and so they let the total dissolved solids rise to the high point of the tds meter and it becomes corrossive,eating everything in it's path.Pools having a tds of 2600ppm is not uncommon.I once called the health department and they closed the pool because when pool water tds was so high.When it gets very much over 700ppm it will not enable the sanitizers to oxidize and disinfect the pool water.This will cause a cryptospiridium outbreak,which can kill infants and the elderly.The one single cause for this disease is any type of diapered children using the pool.