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Re: Tank Backgrounds (long reply follows)
> Date: Thu, 26 Aug 1999 17:16:38 -0400 (EDT)
> From: busko at stsci_edu (Ivo Busko)
> Subject: Re: Tank Backgrounds
> I've been toying with the idea of adding a background to my planted
> tank, using similar construction techniques as described by James Purchase.
> I really would like to avoid permanently gluing something to the back glass
> pane, and the plexiglass with suction cups sounds as a great idea. I couldn't
> figure out however how to handle the potential problems associated with the
> small gap that will result in between the background and the back pane. Water
> could get trapped and stagnant in there. It could be a breeding place for
> small snails, out of reach of the clown loaches. Fry and even larger fish
> could get trapped in there. Sounds to me as a maintenance hassle, or even
> as a potential disaster. Anyone in the list that has experience in addressing
> these problems would care to comment ?
During the development of FakeRocks (see shameless plug below) I looked
at some other types of background and made some prototypes.
Long (but I hope informative) post follows! :)
The first was a simple sheet of acrylic painted on one side with
a waterproof varnish and covered in sand, sand being thrown onto
the varnish while wet. This looked OK (probably would look better
once algae started to grow on it) but for me it was a little flat.
So I started to mess about with polystyrene blocks. This I could
sculpt and make ledges and caves and looked good up until the point
where I covered it in epoxy, the epoxy ate into it so much that it
lost all the detail I'd carved into the foam. Fine if you just go
with it but the result just didn't do it for me. The idea was to
throw sand onto the wet epoxy and build up layers. This has the
advantage that the weight of the sand alone will keep the thing
on the tank bottom, but the disadvantage that the polystyrene has
bearly enough structural stability to support the weight and can
easily snap under the load before you get it into the tank. Also,
in order to get any kind of depth to the caves and ledges the foam
needs to be about 3inches thick which takes up quite a percentage of
the tank volume.
Then I hit it. I cast polyurathane resin forms from actual rock
formations. These are very strong, totally natural looking, and very
It required much more effort but I thought that I want something
that's primarily natural looking (I don't have bubbling divers in my
tank but hey, my son does) and is going to last. If you want to see
the kind of thing then look at my site:
A note about fixing and anaerobic conditions. I use rubber suction
cups to fix these formations. I use silicon to fix the cups to the
top two corners of the formation, the substrate holds the bottom edge
in place. This works fine.
You can attempt to seal the background of your choice with silicon
at the edges (and loose the suction cups) to avoid dead water but in
practice the background can never fit that well against the edges if
it's rigid because most tanks have braces at the top edges or across
the center. Also you have to start with an empty dry tank to do this
making retro-fitting a pain.
I fit backgrounds in two pieces using suction cups and butt the middle
joint a tightly as I can. I accept that water will get behind and use
a powerhead which is used to supply a little extra current during
the day to pull water from behind the formation. The formation sits
in the substrate but doesn't rest on the bottom of the tank so I get
flow under it. The powerhead inlet uses a short tube which goes through
a hole drilled in the formation. I use the powerhead rather than the
inlet from my filter as it's easier to maintain.
I'm playing with the idea of using the top edge as a surface skimmer
by putting a foam insert along the top edge of the formation and
letting water behind the formation that way.
The foam would get cleaned at water changes to remove leaves and gunk.
The thing that's putting me off trying this is that when the flow stops
at night organic matter trapped in the foam may start to turn sour and
in the morning I'll flush this mix into the main body of water.
Too much text ? Ah well, it's done now.