Housing Ball Python - Sterilite?

So, I currently own two ball pythons and I'm looking to get a third.

Both of them are about a year old and I have them each in a 30 gallon tank with aspen, a large water dish, two hides, an under tank heating pad and an infrared bulb. A warm side and a cool side.

I have heard that many use Sterilite containers with locking lids. I have a few questions on this method of housing:

Is a heating pad underneath it safe? As in, it won't get hot enough to do any sort of damage to the plastic, will it?

Is lighting necessary? Because obviously, plastic and heating bulbs don't mix... and if someone has found a way to do it without finding an alternate lid, I'd like to know how.
And if lighting is not necessary, are there any other ways to keep a comfortable temperature in the box outside the heating pad?

Also, what size of Sterilite container would be recommended for an adult ball python?

Thanks in advance!

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Sidenote: The reason I ask these questions is because I recently bought a tank and I have it all set up for my incoming ball python. However, I have recently been considering ALSO getting a baby beardie... since my beloved Jack is coming up on his 8th birthday. They grow up so quickly!

http://www.ball-pythons.net is the best place to find great care for your ball python From my experience the infrared light isn't needed, but you really need to have a thermostat on your UTH's. You put the thermostat probe between the UTH and the enclosure - then adjust it until the closest point that the snake can get to the UTH is at the correct temp.

Oh, and sterilite containers are fine as long as you have the thermostat (which you ALWAYS need)

yeah the plastic tubs are fine and actually are much easier for keeping humidity up. but as was stated a rheostat will help keep the temps from getting too high.

ashleyelsha":1bg97ief said:

yeah the plastic tubs are fine and actually are much easier for keeping humidity up. but as was stated a rheostat will help keep the temps from getting too high.

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Keep in mind that a rheostat and a thermostat are two different things, I rheostat is a decent stopgap while you wait for a thermostat. The thermostat is a true failsafe against a failing UTH. You really don't need (and shouldn't have) lights on the enclosure - lights burn up the humidity and stress out your snakes [such picky animals ]. As long as you have the UTH WITH A THERMOSTAT [man I can't stress that enough] you'll be great with a sterilite tub, they're very popular. That website is really good also - I'm an active member there. Also, make sure you get a tub that has locking lids, missing snakes are worse than missing beardies!