HELP!! What Did I Do?!??!

[AndyL]

Sorry about the loss bev, that CB was awesome!

I wouldn't put a whole lot of stock in the scraping of the cyano as being the cause. Cyano (at least in freshwater) has the ability to fix nitrogen from more than just water borne NH3/4/NO2/NO3. One of the major reasons why planted tanks can have major outbreaks in very nitrogen depleted/limited systems.

I personally would be looking to alternate sources where a toxin may have been introduced - maybe the scraper came in contact with a chemical... New air freshener maybe? There are a million ways a toxin can be introduced into a tank, figuring out how it happened is always a challenge.

Andy