A well-balanced tank contains organisms that metabolize the waste products of other inhabitants. Nitrogen waste is metabolized in aquaria by a type of bacteria known as nitrifiers (genus Nitrosomonas). Nitrifying bacteria metabolize ammonia into nitrite. Nitrite is also highly toxic to fish in high concentrations. Another type of bacteria, genus Nitrospira, on–converts nitrite into less–toxic nitrate. (Nitrobacter bacteria were previously believed to fill this role, and appear in "jump start" kits. While biologically they could theoretically fill the same niche as Nitrospira, it has recently been found that Nitrobacter are not present in detectable levels in established aquaria, while Nitrospira are plentiful.) This process is known in the aquarium hobby as the nitrogen cycle.

Thanks for that, we have some more info here if you're really interested

the nitrogen cycle

Aha, thank you for that...

Er..... Was this a question? An Answer to a question? Or a general statement?

I am confused.

I wouldn't worry JG A reference to a once popular brand of processed tin meat product springs to mind, although of course I could be completely misjudging the situation, in which case I apologise

Would that be the one that Monty Python produced a whole musical about?

I do be thinking so FL. To be honest after so many years in the hobby I really did need somebody to remind me of this most important fact in fishkeeping. The very first thing you should ever learn, such a shame it wasn't brought to my attention until now.

Do you know I think it might be Call me Old Mrs Cynical Or Old Mrs Leaps to Conclusions

Doh, cross posted there, really my Curmudgeonly friend, I'd have thought you'd be au fait with that one by now, dear me, you really must brush up on your basics

I did battle with one such early one morning - we had a contest to see whether he would stop posting before I stopped deleting