Oh, about the 40 nitrate thing. Dollars to donuts it's just interference (ie., the water is cloudy and thus the colour got darker, or something of this nature). It can't have jumped to 40 just like that, so either it's a false reading, or it already was up there or close to it in which case another day of it won't hurt. If it IS 40 though tomorrow, well .. you know. Not to sound like a broken record but there are these lentil like pellet things you might have heard about.
Spawn events are a mixed blessing. On the one hand, it's cool to see because blah blah blah circle miracle of life wonderous times blah blah blah and all that, ... but at the same time IT'S IN YOUR TANK AND IT SMELLS! LOVELY! .... I totally feel for you tonight. But I promise after tomorrow it will be OK again!!!