Don't panic Tom, that's -exactly- what the "Qualification Week" is for!! Think if you'd just put fish in? This may be it! This may be your last big blip before the N-Bac colony finally moves up to the size they really need to be. What this does is reset the start of your qualification week, assuming it drops right back to double-zeros tomorrow or the next day. Remember, it has proved that it can do a lot of double-zero days and it will probably go right back to doing that again. It's biology, not chemistry, and it is quite common for it to give you a wild ride.
Also keep in mind that there is no "fault" here. You have been carefully asking, monitoring and doing all the best practice things as far as I've noticed, so it's important to accept that there are many variables (most of them chemistry that we can't do) beyond our control. Our two species of bacteria are just two among about a hundred and there is competition, potentially, for the best spots on the media - the wwtp folks mention this in some of their literature, so I think of it as one of the possibilities.
Your pH is still 8, so we're not looking at a crash here. Has your nitrate level gone way up?
WD
so tested again +5ppm omg!
right now
