[Myka]

Starboard is a brand of HDPE or high density polyethylene. It is the plastic used for cutting boards; particularly those used in commercial applications like restaurant kitchens and butcher shops. It has a texture to the surface so it is not slippery and commonly comes in 1/16" to 1" thickness. Starboard is used to create a sandbed look in barebottom tanks, and although its use in aquaria en masse is relatively new, it has gained some popularity. Not only does it provide a more appealing look than a glass bottom it also can significantly distribute the rock weight depending on thickness. HDPE does float though, and silicone doesn't stick to it (pretty much nothing sticks to it lol) to you have to use the rocks to hold it down.

I have 3/4" in my tank. I got it from a plastics shop (they do custom acrylic signs and such) and it cost $60 I think. I think I'm going to drill it through part of its thickness and insert acrylic rod to help support my rock structure. The HDPE is cut 1/2" smaller than the inside tank dimensions to have a 1/4" gap all around. I put a bead of silicone around it to fill that gap so detritus and other gunk can't get down between the HDPE and the glass.