I'm new to the forum and had noticed a question that included the biOrb aquarium line. Thought I'd post a review on mine.
These are acrylic, spherical tanks that are filtered via a bubble column that flows up the middle of the sphere. Water is pulled through a disposable sponge/chemical filtration pack at the bottom of the column tube. They come in 30 and 60 liter [@ 7 and 15 gal] sized. At the top is a built-in halogen light [optional] and the tank can be fitted with an optional heater. Key to the filtration system is the high surface area ceramic media that supports a bacterial population for biological filtration. Orignally made in the uk, available in the usa now as well.
The pros here are the stylin' good looks--the base and top trim even come with interchangeable colors--and the fairly simple maintenance routine. You simply twist the bubble column and lift out the filter pack, replace it with a new one, and twist it back in while doing your water change. Another pro is the thriving and helpful biOrb forum on the koivision.com web site.
One of the drawbacks is that, while the packaging and advertising often shows a 7 gal tank with 4-5 happy fancy goldfish, it is misleading to think that you could house even 2 goldies in there comfortably for very long. [Though it IS a step up from a 1 quart goldfish bowl!]
I've used mine for a simple marine set-up, tropical, and as a betta tank. I've kept 2 2-inch fantails in there temporarily. I find it to be best for the small tropical species and for a single spoiled betta.