Its been a while since I posted anything because I've been concentrating on getting my tank back up and running after a disastrous start. Now, my other half is so impressed with our tank, that he wants us to get a much bigger tank, which will sit in, and be a feature of, our fireplace, instead of a fire. This is a real turnaround after he had previously said "we're not having a bloody fish tank!". So I'm now looking at the prospect of having a 40 gallon tank, instead of my current 10 gallon, and getting all excited about being able to buy more fish. Thanks for the advice I received on this site, which was immensely helpful. Onwards and upwards.