Small tropical tank recommendations please

[LiviaAugusta]

I'm looking for recommendations for a small (15-20L?) tropical tank please... I've had a BiOrb 60L for a few years now but have had major algae and space problems with it since we moved a couple of years ago. We've had to move it every 6 months or so from the coffee table (right next to the heater so no good in winter) to the kitchen table (in direct sunlight so no good in summer and the cause of the algae problems) but this winter can't move it again although we need the heating on now! I really want to start again with the 60L tank as it's never recovered from the algae and I want to throw all the ceramic media etc out clean it then start it afresh when we eventually move. We've currently got about 7 fish plus a couple of shrimp in the tank- neon and gold tetras. DH and I have talked about rehoming the fish but I'm not sure anyone would want them really as they've not been living in the best conditions, they seem healthy enough but I'd be worried about someone putting them in their tank!

We do have space on the work top in the kitchen for a small tank though and I do love keeping my fish so am now looking into a small tank but have no idea which one! I'm not keen on getting a smaller BiOrb as I'd like something square I think (and DH complains the BiOrb makes his eyes hurt!). Any advice?

I have a small rectangular 20l tank that I got from a pet shop quite a few years ago, I use a small 5w heater with it and a small filter.
It was originally bought for DD1's Molly but is now used as my quarantine tank. It would be fine for 7 tetras but I would aim to get your bioorb back up and running as soon as possible.
I'd also be prepared for most of your fish to cark it when you move them if they aren't in the best of health before hand.
Don't forget to set up the new tank and cycle it using some of the filter media and gravel from your current tank, testing it for nitrites, nitrates and ammonia before transferring the fish.

I would avoid anything less than 60 litres. These little 15-20 litre tanks are aimed at beginners but they are bloody difficult to maintain because a tiny change in water parameters can spell death for the entire tank. Also they are too small for most tropical fish. 60 litres is manageable and if you get a decent filter and maintain it so that the good bacteria don't get killed off then it'll be a lot less work than your Biorb- Biorbs look great but they are a rubbish design, hard to clean and maintain and no good for fish.

http://www.fishkeeping.co.uk/articles_51/fishless-cycling-article.htm This explains more about the nitrogen cycle that mrspnut mentioned.