Do 3x15x18 tanks need a centre brace?

[mark freshwater]

Hi,
I have a 3 ft with a centre brace that will be in my road,
im going to put baffles in it for a sump,
can i take the centre brace out or is it structural?
Thanks
Mark

 

[mark freshwater]

Also can i take out the side braces/lid holders as 1 is broken

 

[mark freshwater]

Also the left brace/lid holder is brocken a bit, should make a new one or take it off ?