no joke man, if the tank really collaspe, imagine the weight almost about one ton. and it could even go thru your floor to your neighbout downstairs.
you will not want to be sue by that, rite?
Mine is also built in tank. for latest built in tank, i would say Sugi's tank(member's tank) is the best design & safest.
so for short term solution : u might want to take care of the stand first- . chang gei wood is good but must make sure the wood touch the floor & not just to the base only( normally for designer, they like to make the base which is hollow inside)
Long term wise, re-do it . so that you could sleep at night without nightmares.
How Sugi? I promote your tank leh..