[bigdheel]

During my research in preparation of setting up my first planted tank I have seen some photos where people are putting down the light fixture grids on the bottom of the tank. The white plastic 1x1 square covers that are for lights in a business or school. I think they are called egg crate by most.

Anyway, what is the point of this?

 

[lauraleellbp]

They can be useful in creating a level, stable base when people are trying to build elevation into their aquascape with "mountains," "trees," etc.

There are some other uses, but that's the most common one I've seen in recent years.

 

[Whjdm069]

I did it to add levels but have heard if you want to use stones that it's good to put it down. I also was able to zip tie a piece of wood to it. It allowed me to stand it on end and not fall over. If your burying anything to the bottom it Keeps it off the glass.

 

[Acro]

I think it's normally called "egg crate". Here is a good example of it's use: http://www.plantedtank.net/forums/showthread.php?t=595162

 

[PlantedRich]

For those who missed out on real eggcrates, the name may be a mystery. Before egg cartons formed from styrofoam, eggs were shipped in crates. Inside the crate there were layers and each layer had a cardboard grid which seperated each egg. Looked much like the plastic light diffusers we sometimes use.
But then whether they are good or not is still hotly debated. They have their uses as mentioned but they also can be a real pain. I don't use them even though I use lots of rocks in my tanks. A scratch on the bottom glass is no problem to me as it should stay covered anyway. What I don't like is when my fish are digging and expose the really artifical looking eggcrate! I paint my tank bottoms black on the outside to avoid the shiny reflection. Also when trying to get the grung out of the substrate in unplanted tanks, I find the eggcrate makes it impossible to syphon down to the bottom.
Like other things, some find it useful, some find it a nuisance. Certainly not required but it can be handy.

 

[lochaber]

I've also heard of people using it to prevent scratches from rocks and somewhat to help redistribute weight.

On smaller tanks, I just use a piece (or 2, or 3) of the plastic canvas stuff, it's thinner, so it doesn't take up much room, but it will help prevent the bottom from getting scratched.

Mostly cosmetic, and since it's covered by substrate, bottom scratches are rarely noticeable. However, a lot of the larger tanks use tempered glass on the bottom, and if those get scratched the whole pane will shatter, so a piece of eggcrate can be a very important safety item when using rocks.