Spray foam and rock.

[KevinK]

forgot to mention that when it is in the water, the foam tends to schringk about 1/8 ore so.

this means when you spray it directly on the glass for a back wall, it could over time get loos, becouse it pulls itselve off by schringking.

other nice thing is that laterone you could gust plug in a frag, without the always ugly frag disc.

the ledge you se on the last picture isonly black foam covered in coraline algea, I put the galaxy on top of it and i sticked all other corals directly in the foam