You place it on a shelf, can use aluminum tape or even electrical tape to keep it in place. And yes, just place the containers right on top. It's water proof, and the clear covers will help keep the connectors from shocking you/getting wet. I cover them over with electrical tape just because I'm paranoid like that.. I also place electrical tape on the last edge of the last piece of the flex that don't have connectors on them.
As for thermostats.. any will do pretty much as the connection wire you order through there has a plug on the end to plug it into any thermostat. I just got one that is used for reptiles, unsure how good it is as I have nothing to compare it to.
To make layers (as on a shelf) you will just use basic lamp wire from a hardware store to connect them.. that is very cheap.
Basically this is what I got -
(Make sure to put together before plugging in) Flexwatt
(You will want to measure the width to get the right one to fit where you are placing them on, and the length total of what you are planning). The new Flexwatts (which you will get if you order through the Beanfarm (which was the cheapest I found) is a new style that don't have the dotted "cut" line, rather you just cut it to your exact length. Razor blade or box cutter
(unless you are good at cutting straight with scissors). You will want to cut between the black stripes, don't cut into the black stripes. Lamp wire
pretty cheap, so can get extra.. just measure the distance between the shelves, etc and add them up.. I got extra because a couple times I had to redo a connection and it was easier to just cut and restrip the wires. Toenail clippers
(the large kind) - can cut the wires to the length you want using them, can also use them by gently cutting into the rubber and then stripping.. if you have wire cutters or wire strippers than no need for the clippers.. I just went simple. Electrical tape Aluminum tape
(optional) Flexwatt Cord Set
If you plan to run more than 15 feet or so then I would order 2 of them. 3 if you want to have a back up for any reason. Clip Sets
There are 2 metal connectors and 2 plastic covers per set.. you will need 1 set (2+2) per connection/row/shelf. So say you have a 6 shelf book case you are using - you will want a set per shelf = 6 sets. I HIGHLY recommend getting at minimum 3-5 extra sets as sometimes things happen and once you close them you can't get them open without destroying the set. So if for some reason you have to redo a connection, you will be thankful for having the extras.. it's well worth it. Thermostat
- you will want one like this
(I can't remember where I got mine from :( But it's similar..) you do NOT
want a dimmer, as you can't control it as easily, and it doesn't have the safety feature of shutting off when it gets to the correct temp like a thermostat does.
I just googled and youtube searched for the flexwatt - you will find people setting it up for under reptile containers, but it's the same set up as what you will be doing (connecting it together). It's pretty simple and it works great.. I tend to have to keep the thermostat up a few degrees higher than what I am wanting, but it does keep it steady at what I want. It comes on and off as needed (tape down the part of the thermostat that detects temp to the flexwatt itself, as that part can't be in water.. that is why the temp of the thermostat needs to be a few degrees higher). It saves on electricity, and it's barely warm to the touch when the thermostat is on, when it's off it's cool to the touch.
It's safe to place on plastic, acrylic, wood of all sorts, some even use styrofoam under it.
I LOVE it.. had too many issues with the water in the tub thing, rather not risk mosquito breeding in the room, etc.. and eventually the outside of the containers become gooey, etc. This has made things so much easier for me, including being able to see the fish and water changes.