I always wondered if, in that application, you would get continual leaching of the alkaline materials into the water. I don't guess that it's a problem but I suppose if it was an issue, you could seal the concrete. For backgrounds you might wnat to use what's called "plastic cement", which isn't made of vinyl but is portland cement with an added resin that lends terrific plasticity to the wet mixture and increased resistance to water penetration.. If the water is acidic, it will slowly eat away the concrete, but that will take years and years and years and years, unless you keep very acidic water. You can see the slightly acid rain do the ame thing to sidewalks in the northeast USA, but you have to watch for a long time ;-) --- Dave Mosley <dxm1@cwnet.com> wrote: > S. Hieber wrote: > > > [snip] > > > > I think that's neat. Relevance? Uh, you can use > portland > > cement to make a pond base. > > Also to make nice 3D aquarium backgrounds... > __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com ------------------ To unsubscribe from this list, please send mail to majordomo@thekrib.com with "Unsubscribe aga-member" in the body of the message. Archives of this list can be found at http://lists.thekrib.com/aga-member/