Hi Guys Its nice to know I can come back to hear after a few years when something completely foxes me like it has just recently. I was down to 1 guppy after my others had died so I got him 2 ladies on Christmas Eve, to live out his retirement happily. I know I should have 6 but didnt want to overload the tank and I figure 3 is better than 1 lonely one. And they all play with the Platy's happy enough as a shoal. I did partial waterchange as usual. Aqua safe and a glug of sure start as I was adding the 6 platys at the same time. I also added some new plants. By boxing day, 1st wift is gone - no sign of a corpse - but not unusual in my tank - I think the upside down catfish did a midnight clean up mission. Tested water - Ammonia 0, Nitrite 0, Nitrate - cant remember exactly but about 25ppm. I think its usually about 10. Did another partial waterchange - not too much - about 10%. I didnt want to shock the critters. Then I realised night before last wife 2 croaked. She must have only just died so i scopped her out - she was preggers when I got her so wondered if there was some child birth complications or some such as I have some baby fry in there now. Tested water - Ammonia still 0, Nitrite 0 nitrates 50!!! I dont understand how i got a Nitrate Spike - without the others going up first - whats more - a 50% water change didnt seam to bring it down much. I am doing lots of Partials but it would be good to know what I did to get it to spike Like that. Also, do you think the spike killed the guppy ladies or the deaths caused the spikes and very rapidly went from Ammonia through to Nitrates?! The Neons and Corys are all fine - and they are always first to tell me if something is not right?!