I have also purchased one of the `Fish R Fun` UV sterilisers and would recommend it to anyone. They are very cheap and couldn`t be any easier to install.
http
/www.rocketrading.co.uk/product_info...4abb81db18ac77e
They come in two sizes: the smaller (which I use in a 180 litre freshwater tank) is around 25 quid delivered, the larger is around 50. Replacement bulbs are reasonably priced too.
It is an independent unit, so doesn`t have to be plumbed in-line with your existing external filter - with all the accompany worrying about correct flow-rates through the steriliser, too much head pressure, more joints to leak, etc. So, you sucker it to the inside of your tank in the same way as a heater, trail the wires to wall socket and that`s it. Within the housing of the `Fish R Fun` UV steriliser is a small pump with an inlet/outlet to draw your tank water at the correct flow-rate over the internal bulb.
I`m still building the stock levels in this particular tank, and over the past six months I`ve had no white-spot problems passed on from new introductions at all - even though a couple of those new introductions have flicked for a short while. My water is crystal clear, and I haven`t bought any meds for six months either - which is good because I keep ADFs, nerites and shrimps too.
Some on here might consider them a little `mickey-mouse`, but the results I`ve had from these cheap little UV sterilisers have been brilliant. (I have no attachment to this company BTW, just an impressed owner having been similarly recommend of these).
[edit: they are a little bigger than they look in the photos, so stick to the smaller one if you fall in its range]