Lego Batman Strategy Guide 87: Green Fingers, Free Play, Part 2
The fountain area has a lot of things to find. You must become Diving Suit Robin and make your way toward a circular opening on the floor. For some reason, going into this opening puts you behind a door, where there is a lever. Pull that lever, and the doors will open. You will see a view of the fountains, and one of them will have the Fifth Canister up on top.
When you get here, there is a tree that has some studs up on top. Take some time to use it, as the studs on the top area quite valuable.
You will soon get to the one area with all the toxic waste on the floor. There is a glass box here, so use the Sonic Suit Batman to shatter it. You will then have a bunch of metal tiles that can be built to go along a wall, and Magnet Suit Robin needs to walk up there and to the right to get the Sixth Canister.
When you get past this room, you will be in an area where there is a glass room on the left. The entrance can be blown open with an explosive. Go on and go in, and build some metal wall out of the many pieces there. You will need a super strong character to move it into place with the orange handle. Go ahead and become Magnet suit Robin and walk up the wall. Turn left up there, and walk over the partition and become another character so you can fall and get the Seventh Canister. Take the ladder up and get out of there.
Soon you will come to a batrope area, right near some hot hot pipes. Go ahead and become Batman in his Heat Protection Suit and use the batrope area to get on the pipe. Take the small circular door on the right, and you will be in the area with the Eighth Canister.
Keep going all the way to the right, and you will see a glass door. Take it out with Sonic Suit Batman’s sonic blast. You will then need to become Water Suit Robin and go into the next room. Sink to the bottom, where you must hit a button. A partition between two tanks will open, and you can go over to the other tank. Eventually, it will fill back up, and you can grab the Ninth Canister. Drop down and hit the button again, and go through the partition again, and back up to where you need to go.
As for the last canister, it is found in the one final area. There is a silvery plantbox here, and if you blow it up with an explosive, you will have the Tenth Canister.