Tank Crashed: What does it mean?

[filippo]

hi

What happens when a tank "crashes"?

I believe it has nothing to do with the actual tank (no physical damages to the glass or acrylic). does it mean that fish and corals die all of the sudden, or that maybe all water parameters raise? or that maybe some other chemical reaction happened?

I think I have an idea, but a definite answer would be lovely

thank you

[JR719]

When your parameters, or something else, causes mass death.

[Sk8r]

YOur parameters as they should be:
temp 80; alk 8.3-9.3; ph 7.9-8.3; calcium 400-450; mg 1200-1500; salinity 1.024-6....oxygen plentiful.

A 'crash' means a variance in these parameters, particularly oxygen [supplied by skimmer, downflow, and refugium, and least of all, but most basic, the pump]---in which one fish dies, raises ammonia [s/b 0] and things go to hades in a handbasket, as inadequate clean up crew fails to take out the dead fish fast enough, sandbed isn't strong enough to reduce dead fish to nitrogen gas fast enough, next fish dies, nitrate/ammonia gets worse, oxygen gets less [or caulerpa spawns, or corals spawn, and spawn rots, same effect as big dead fish], etc, etc.

This is where a mature sandbed, modest stocking, and a large cleanup crew including many, many bristleworms and some nassarius snails will save your tank.

[filippo]

thank you both