My adult setups were designed to allow me complete control over my diamondback terrapins environment. I use 150 gallons Rubbermaid stock-tanks for all of my breeding setups. They can be ordered through most feed stores.
All of my tubs are stored inside of my garage, which is heavily insulated. I live in Los Angeles so the summer air temperatures easily reaches the 90s during the day, this helps keep the water around 78F. During the day I open vents to let out the humidity and I close everything up at night to hold the warm air inside.
During the winter I open the vents at night to help cool down the garage and during the day I keep them closed. This help keep my water temperature to around 55F.
There are a lot of options when it comes to filtering a stock tank. I personally like wet dry filters. Most can be run with an submergible filter that moves at least 300 gallons per hour. Tetra Pond: PF-3 Clear Choice Biofilter is a very reasonably priced wet-dry filter. I have used them on 150 gallon to 300 gallon tanks. I suggest changing the bio-balls the filter comes with and use ones with more surface space. I personally have use Bio-Bale in these filters.
It might sound like overkill but I like to turn over my water about 3 to 4 times an hour. UV filter also are great for helping keep the water very clear.
A simple standalone breeding setup with a 150 gallon Rubbermaid stock tank.