What is the definition of a tank crash?

[Wayne]

I think I might be on the verge of a tank crash. SPS is dying, leathers have been shedding skins for weeks, zoas closed up, clam only half open.

Fish are fine, levels for ammonia, nitrite, nitrate are zero. Magnesium was around 1360, calcium around 400, PH 8.0-8.2, phospates are high at 0.5, KH at 10.

I have been doing small water changes everyday for the last 3 days, without disrupting the display tank with some visual improvment in the LPS. Am I on the verge of a crash and how do you prevent...

P.S. This happened a month ago aswell and the cause that I believed was the GFO and Carbon I was running in a reactor. I have since thrown all that mixture away and put a little carbon in. After seeing the problem again the first thing I unplugged was the reactor.