For starters a 50 gallon is way too big for a young BP, the absolute biggest I would go is a 24 x 24 inch cage.
If you intend on having the pond be the snakes water dish just say no. You need to give your snake fresh water every few days and having it in a non-removable container will be a nightmare (the filter isn't enough) further BP's don't need a water dish big enough to soak in. The largest water dishes that I use are 8" diameter. As long as your humidity is in the proper ranges your snake shouldn't be soaking unless something is wrong. If it is too deep there is a risk of drowning.
When using any substrate a UTH will have to be set higher than if you are using something like paper towels. UTH's can only function if the substrate is 1/2" thick or less. Any more and they make the floor of the cage too hot to be safe.
Screen top: http://www.thatpetplace.com/screen-c...ey_id=26447074
These are the best hides out there: http://www.reptilebasics.com/hide-boxes
Ultratherms are great, but zilla reptile temperature controllers are junk. Don't waste your money on these. Here are some good thermostats. avoid thermostats sold in petstores as they are overpriced junk.
Budget: http://www.amazon.com/Hydrofarm-MTPR.../dp/B000NZZG3S
Mid-Range: http://www.reptilebasics.com/ranco-etc-111000-pre-wired
Best: http://spyderrobotics.com/home/products.html
Keep in mind that UTH's do NOT increase the temperature of the air in the cage. this means that if the room that the cage is in drops below 75 degrees a heat lamp or Ceramic Heat Emitter will be necessary to keep the air temperatures up. (50 gallon tanks are near impossible to easily keep proper temperatures and humidity in)
That acu-rite model isn't what you want, you need a probed thermometer. This acu-rite model would be much better:
I strongly suggest that you read these 2 threads, and look into other cages. I personally like PVC reptile cages (pictured below) but tubs or even smaller glass tanks work too.
Care: http://ball-pythons.net/forums/showt...ius)-Caresheet
Cage Heating: http://ball-pythons.net/forums/showt...t-Thermometers
When it comes to Ball Python cages simpler is better. Everything inside a cage is going to have to be regularly disinfected so the less there is the easier that will be. Many people would consider this to be the ideal BP cage setup.
Here is what a PVC reptile cage looks like (they hold heat and humidity in much better than glass tanks do, and they provide more security to the snake)
![]()