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Sand/gravel background



Paul wrote:

>I used to make cave or hut-like structures for kribs out of slate pieces
>glued together with silicone, and, after a few years, they fell apart.
>Apparently the silicone does not stick to the slate as well as it does to
>glass.  Maybe they have varied the formula for silicone so that it sticks
>better, now, but I would worry about the silicone holding pebbles for long
>periods of time.  It would probably hold onto smooth, shiny pebbles the
>best.

This has been my experience as well.  In my paludarium which is now 6 1/2
years old, within the last year pieces of slate have started to peel off
here and there.  I don't know if there is a good, easily available solution
to this problem in a long term tank.  I suspect that the majority of people
don't keep a tank running for this long anyway, so it might not make that
much difference.  

In the case of my own tank, I have just been very lucky.  I happen to have
a friend who is a dentist.  He offered to cement the loose piece back in
place with dental cement.  Since this is meant to cure even in damp
surrounding, set up quickly, and remain solid for years in a person's
mouth, it sounded like a good option.  We drained the water down past where
the pieces had fallen off, towel dried those sections, and he went to work.
 He found that it takes a _lot_ more cement to stick rocks back than to fix
teeth.<g>  The cement set very quickly, and we were able to refill the tank
before the plant leaves started drying out.  

Our only slight concern was that this cement does contain small amounts of
fluoride, and we weren't sure how that would affect plants and animals in
the tank.  Since the cement has been in place for about 9 months now, I
feel confident that it has not had any negative impact on the inhabitants.
As far as how long it will last is concerned, check with me in another 6
years ;-)


Karen Randall
Aquatic Gardeners Association