Looking at Juwel's website, they say the tube is a T8, which is good news if you want to stick with a fluorescent tube. You can check that it is T8 not T5 by looking at the width. T8's are an inch across while T5s are 5/8 inch across.
If you can confirm it is a T8 you can replace it with any other T8 tube the same size. (T5s are different because Juwel's are a slightly different length from most other brands, though Arcadia do make Juwel compatible T5s). The thing to look for with replacing the current tube with a different brand is the colour. Some emit white light, some pink light and some yellow light. Research first before buying! And you don't have to buy tubes made for aquariums.
Another alternative is LED lighting. There are LED tubes which will fit into T8 lamp holders. Some can be powered by the fluorescent light's ballast but be careful as I've read that some can only be used with fluorescent ballasts with magnetic starters; they won't work with electronic starters. Alternatively there are some LED tubes which have their own power supply and come with plastic ends which slot into the fluorescent tube's holders just to hold them in place - but in this case do not plug the original plug into the mains. You could cut the cable off but that would probably invalidate the warranty of the whole tank. When I had a Rio, I think the warranty was void if you so much as removed the built in filter.
Of course if you are handy with diy, you could rewire the whole hood for a cheaper, non-aquarium LED, but again that would probably invalidate the warranty.
I have gone down the route of LED tubes that just slot into the fluorescent holders and with their own power supply. I much prefer them to fluorescent tubes.
