Floor - To brace or not to brace??

[WarDog]

I have to second gregzz4 on this one. That structure will handle the weight no problem, but your tank will bounce a bit for sure. For $100 of lumber you can sleep better at night.

[mark]

am I missing something, it's only a 6' span, where's all this bouncing coming from? Planning a party between the tank and those side walls?