plastic stuff at the bottom of tank

[saltyfishwater]

I'm looking for aquascaping ideas for a 29 gallon biocube, and I came across this aquascape where they used these white plastic stuff at the bottom of the tank.  What's the function of the plastic?  Does it get in the way of sand-sifter fish?

 

[image attached]

 

Thanks!

[empresto]

That's called egg crate. It's sold at home improvement stores as light diffuser for large florescent fixtures. That person is probably using it to protect the tank glass from the rock placing pressure on the small points where it makes contact which could cause cracks later. They may also be attaching that structure to the egg crate to add some stability to the scape.

I used egg crate in the bottom of my 18gal to protect the glass from the rocks. Hasn't caused any issues; occasionally I get to see a bit of it in the corner of the tank when a power head decides to point a bit too low, but usually the sand is more than converting it. It's less than a half inch thick.

[Tired]

Fish that sift an occasional bit of sand but don't rely on it, like watchman gobies, should be fine with the eggcrate. Fish that rely heavily on sand sifting, like sleeper gobies, should have a deep enough sandbed that the eggcrate would be more than covered. 

 

Of note: fish that sift sand for a major part of their food should only be kept in large tanks with deep, well-established sandbeds, and are bad for said sandbed due to eating a lot of the microfauna. Exclusively sand-sifting fish are hard to keep in captivity. Fish that sift a little sand now and then, like watchman gobies, are fine.