established African tank crash

[srikamaraja]

Has anyone ever had an African rift lake or similar high-ph system crash after a more than 50% water change?
This happened at the LFS I work at, after the tank was installed (one huge water change, at least 70%) and again after it was moved across the store floor (same amount). pH and alkalinity were preserved, and two weeks later, all readings are normal. There never was a bacterial 'crash' per se, just a massive die-off of the roughly 30 mbuna cichlids in this (rather tall) ~50gal tank.

 

[Toodleypops]

wow thats crazy!! i have no clue at this point. COuld one of them had a disease??

 

[mercury904]

maybe a diffrent culprit

 

[dragonscrawling]

Did you check ammonia and nitrite? I have had a number of tanks sky rocket in no time after moving them due to disturbing the gravel. It is usually nitrite, haven't had any fish die because I have recognised it and dealt with it. Just a thought.