# [Wet Thumb Forum]-substrate space filler



## JERP (Feb 4, 2003)

Does anyone use anything other than rock and gravel to fill space in the aquarium substrate? I'm doing some heavy duty terracing and was looking for lightweight filler. I would rather use a few large plastic bricks than an extra 300lbs of rock and gravel. This would also allow me to keep the substrate 2-5" deep rather than 10-15" deep.

The black expanding polyfoam is a great idea. I was wondering what else people used.


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## JERP (Feb 4, 2003)

Does anyone use anything other than rock and gravel to fill space in the aquarium substrate? I'm doing some heavy duty terracing and was looking for lightweight filler. I would rather use a few large plastic bricks than an extra 300lbs of rock and gravel. This would also allow me to keep the substrate 2-5" deep rather than 10-15" deep.

The black expanding polyfoam is a great idea. I was wondering what else people used.


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## Hawkeye (Aug 20, 2004)

I have used plastic milk jugs cut and placed upside down. I all so have used plastic flower pots. I would tie a small rock under them just to hold them down until I place my substrate over them.

Hawk


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## JamesHoftiezer (Feb 2, 2003)

Tupperware/Rubbermaid

It has the flat shape you may be after and is cheaper than many gravels by volume.

Just keep in mind that most volume fillers are going to be bouyant. You will still need a godd sized layer of gravel to hold the filler down.


There is also a slightly bouyant rock filler. Its called LECO and is used in terrarium construction for much the same purpose. It will float but is an excellent compromise. In an aquarium I would keep it in mesh bags under the gravel. Deep rooting plants will still have room to expand, it just won't be into thick gravel. The pellets are ceramic and average 1/2" dia.


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## imported_Piscesgirl (Feb 19, 2004)

I would like to add a warning about anerobic bacteria build up in situations like that. I had an ornament that was hollow on the underside, and it would build up hydrogen sulfide (or whatever, terrible rotten egg smell), even in the substrate around it. I finally got rid of it and if I put pots in a tank, will put a hole in them (contrary to some who say fill holes) so that there is some exchange of gasses/air.


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## JERP (Feb 4, 2003)

I had considered tupperware but I would prefer a solid media to prevent anerobic bacteria or bouancy problems. I may just get some lava rock gravel (2"-3" grains) from the garden shop. It's lightwieght, solid, and sinks. Mixes with gravel, it could provide a solid base for terracing. It's nt nearly as light as a hollow container but it is much less dense than regular gravel.


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## imported_timlawyer (Jul 14, 2003)

What about using the tupperware container, but punching a few holes to allow water to flow in and out - wouldn't that avoid the anaerobic bacteria problems?


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## JERP (Feb 4, 2003)

I ended up using crushed lava rock. I got enough to fill a 5gallon bucket for $3.50 and is wieghed about 12 lbs. That achieves my goal of finding a substitute for gravel when terracing. Lava rock is light stuff. For $3.50, it's as cheap a solution as I can think of.


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