I have two obsolete 115ltr tanks, one I used as a drying/preheat tank the other as a bubble/settle/dispensing tank, both are free standing.
The wvo tank is 400mm diam and the bio tank is 300 x 450 both are approx 900mm long. They've served me well over the years.
FREE to a goodish home.
I'll see if I can get a picture of them posted.