A week ago I decided to rescape my tank with a sunken city look, but I could not find any decorations at my LFS that gave the right impression I was looking for in my kids' colorful (very colorful) 26 gallon tank. I then thought of looking for a Lego set that might fit my imagination. I had good timing as Lego released set 7985, City of Atlantis, for 2011:
IMG_1518 by Gvilleguy, on Flickr
IMG_1519 by Gvilleguy, on Flickr
After reading other Lego threads on this forum, like this one:
Tank Concept
I decided it might be prudent to construct the set under water to keep it as "heavy" as possible and avoid it floating in the tank. It was more work than I expected, as each individual piece took a lot of spinning and flicking under water to get all the air bubbles out. But it worked out okay. I filled an unused 5 gallon tank with dechlorinated water and constructed different phases in there before transferring to the main tank.
IMG_1520 by Gvilleguy, on Flickr
IMG_1521 by Gvilleguy, on Flickr
IMG_1524 by Gvilleguy, on Flickr
IMG_1525 by Gvilleguy, on Flickr
The first two levels sunk in the main tank, but still required a few small rocks (visible on second level) to keep it totally down:
IMG_1527 by Gvilleguy, on Flickr
Last remnants of the old decor on the left before it was all removed:
IMG_1528 by Gvilleguy, on Flickr
Completed main building:
IMG_1530 by Gvilleguy, on Flickr
And the final version with the smaller columned pieces on the left, plus new (fake) plants added all around. The only real plant is the java fern on the fake log on the left:
IMG_1544 by Gvilleguy, on Flickr
IMG_1553 by Gvilleguy, on Flickr
IMG_1557 by Gvilleguy, on Flickr
I was inspired by the manually activated door lift to put an air stone underneath, and added weight with a flat rock and rubber bands, so the door lifts every 10 seconds or so to release bubbles:
IMG_1559 by Gvilleguy, on Flickr
Here are shots with the moonlight LEDs:
IMG_1572 by Gvilleguy, on Flickr
IMG_1573 by Gvilleguy, on Flickr
IMG_1574 by Gvilleguy, on Flickr
And here is a brief video showing everything in action:
IMG_1518 by Gvilleguy, on Flickr
IMG_1519 by Gvilleguy, on Flickr
After reading other Lego threads on this forum, like this one:
Tank Concept
I decided it might be prudent to construct the set under water to keep it as "heavy" as possible and avoid it floating in the tank. It was more work than I expected, as each individual piece took a lot of spinning and flicking under water to get all the air bubbles out. But it worked out okay. I filled an unused 5 gallon tank with dechlorinated water and constructed different phases in there before transferring to the main tank.
IMG_1520 by Gvilleguy, on Flickr
IMG_1521 by Gvilleguy, on Flickr
IMG_1524 by Gvilleguy, on Flickr
IMG_1525 by Gvilleguy, on Flickr
The first two levels sunk in the main tank, but still required a few small rocks (visible on second level) to keep it totally down:
IMG_1527 by Gvilleguy, on Flickr
Last remnants of the old decor on the left before it was all removed:
IMG_1528 by Gvilleguy, on Flickr
Completed main building:
IMG_1530 by Gvilleguy, on Flickr
And the final version with the smaller columned pieces on the left, plus new (fake) plants added all around. The only real plant is the java fern on the fake log on the left:
IMG_1544 by Gvilleguy, on Flickr
IMG_1553 by Gvilleguy, on Flickr
IMG_1557 by Gvilleguy, on Flickr
I was inspired by the manually activated door lift to put an air stone underneath, and added weight with a flat rock and rubber bands, so the door lifts every 10 seconds or so to release bubbles:
IMG_1559 by Gvilleguy, on Flickr
Here are shots with the moonlight LEDs:
IMG_1572 by Gvilleguy, on Flickr
IMG_1573 by Gvilleguy, on Flickr
IMG_1574 by Gvilleguy, on Flickr
And here is a brief video showing everything in action:
and good that the kids like it too! 
