I found a product called a "floating island ecosystem" on a pond equipment site. It's an island that floats, just like it says. Kinda cute, and maybe also a place for fish to hide under, away from the sides of the pond.

They say that it adds biological filtration to the pond, and since I decided not to have rocks in the pond (which some say adds places for beneficial bacteria to grow) I have been looking for alternative homes for the BBs.

Has anybody used one of these?

I think I've seen those, but I have no clue what they have inside them that is supposedly helpful. I'm thinking they have desiccated bacteria inside the part that goes into the water that is supposed to become activated when it's re-hydrated. I have no idea how long it would last though. However, as you mentioned, it's probably just a giant piece of bio media meant to cultivate nitrifying bacteria.

The pictures have plants growing on it. I managed to find a detailed description, and it says that it has some kind of porous mat with growing media placed on or in it, and plants are planted on it. The roots go down through the mat, and dangle in the water. From there, it says the plants are more efficient at doing their bio-filter job than plants in a pot. I don't know if additional bio-media are involved or not, but that would seem like a good idea, too.

Some pond equipment sellers say that one needs rocks in the pond to provide sufficient places for the beneficial bacteria to grow. I might try this in lieu of the rocks (yes folks, I've been convinced!)

This could also provide hiding places for the fish not near the edges of the pond. Don't know if a heron could land on it, though...

How does the saying go, believe none of what you read, and half of what you see? Anyway, it looks like it could be worth a try.

Do not rock the bottom.... big mess in the future and really hard to clean up. Plus the smell is outrageous.

Those planters look pretty neat - I have seen some gorgeous ones at SeaWorld a couple of years ago. If you don't use any soil that has added fertilizer in it, your fish should be fine.