Is the hide so that she will snuggly fit? it should be of a size where you're sure she'll just squeeze in.
Add another hide and some clutter - fake plants crumpled paper etc or if the two hides and water bowl take up substantial space you may not need to.
Below are two of my rubs, the smaller has my spider (hatchling age, under 100g) in and two rubs and a water bowl, he is calm and eats well. The larger is for my het albino boy, he also eats and handles very well. He came in the big tub and didn't have a hide so I went out to buy him one which just fits but he seems happy enough :)
My smaller rubs (9l) are set up very similarly to the 12l my spider boy is in but are more cluttered as there is less room for the hides and bowl. If your BP is young (forgot to check before I started writing) a 30l is large! BP's usually stay in a 9l/12l for quite a while (up to around 300g ish or more) it may be that it is too big for her. By cluttering you can keep the current tub. A 36-42l is big enough for an adult BP!
Hope this has helped a bit :)
https://fbcdn-sphotos-h-a.akamaihd.n...6d1898bf056e7a
Edit: Is there a lot of foot traffic in the room she is in? Sometimes this can cause stress as they can feel when people walk by and if this is often it can contribute to a stressed BP. :)