yeah . the KDF is the same stuff they have been using to treat water for human consumption for years but that doesnt mean that it isnt made from copper. it was designed to make water suitable for human consumption.
copper is as i understand it an algicide and biocide so it kills germs and algae just because its copper. but in even to humans it can be fatal in high doses ,causing liver and kidney damage and even death ( according to this site :
http://www.globalhealingcenter.com/heavy-metals/dangers-of-copper )
so from what i can gather the advantages of the kdf filter are that it uses copper (and zinc) to kill bacteria, algae's and fungi (isnt that what the chlorine in our tap water does ? ) . . .. so , if your drinking it yourself straight from the filter then yeah thats fine. but if your leaving it in a bucket over night or maybe in a fishtank for a day then its going to want treating again isnt it ? the water isnt constantly running through the filter after all. its just topping up.
it seems that people are using the hma filter to take out things in tap water that are potentially harmful rays (like chlorine etc) by using something that is even more harmful to rays (ie copper) to do it :s
like you said before, the activated carbon elsewhere in the filter most likely removes most or even all impuritys cause by the copper but ..... what if you over run your filters . what if you ( or anyone else ) put the filters in a different order. what if the carbon in the filter is used up particularly quickly for some reason (they put extra chemicals in tap water from time to time right ?) or something else ?
as far as rays are concerned is the copper containing KDF media a good way to filter our tap water ? or would it be better to just run the tap water through carbon based filter that doesnt contain KDF media ?
or even two types of carbon filter like this one -
http://collinswaterproducts.co.uk/product_info.php?cPath=110&products_id=147 *no KDF version*)
ive already made my choice but i wondered if it would be of interest to anyone else.