[Rainfrog]

I think I can help.

There is no black Great Stuff. The black Foam is handy-Foam. From what I have heard if you can get HF use it. It is a superior product to GS but more expensive and can be hard to find (I can’t Find a distributor) With HF it is not as necessary to cover the back in silicone HF will stick better. I have spoken to PDF Breeders that swear by it and say they have had tanks for years and the hold, well, held. Also HF cures fast, within 5 to 10 minutes the surface hardens and you can start to manipulate shapes you want by pressing the foam around (Use Gloves). Also I have been told it cures with less air bubbles. If you use HF I would recommend Gorilla Glue to attach coco fiber to the foam. Follow the directions and it will work great. With GS Silicon the back both for grip and GS looks like crap. Let cure for at least 24 hrs if not as many as 48 to be sure. When ready to apply coco fiber coat silicone in small sections and press plenty of excess fiber in to make sure you cover. If you try too large an area the silicone will start to dry and the fiber wont stick.

Egg Crate (light diffuser panel) is used to make a false bottom. If you don’t want a false bottom you can make a drainage layer out of a layer of expanded clay pellets 1 or 2 inches deep. You need to cover the drainage layer with a barrier to keep the substrate from packing into it. You can use screen but I prefer Weed Barrier. I just picked up a 3' by 50' roll for $13 and some change at home depot (love Home Depot!) it is fine grade and will let water through but no soil.

For a false bottom use PVC to raise Egg crate off the ground to the desires height. Cover EC with screen or Weed Barrier, then place and inch or so of Clay pellets and then another layer of Screen/Weed Barrier, then the soil. With a false bottom you can leave an open area for a pond, use filters and pumps under the raised floor.

In either set-up make sure the water level is at least a 1/2 inch below the level of the soil or you will get a boggy mess. Proper drainage will keep your plants healthy and help prevent root rot (Smells BAD)