Over the years my tanks have gone something like;
Early 1997; 10g
Few months later; 10g + 30g
1998; 75g + 30g
2000; 150g + 30g
2002; 40g (moved out of home and went flatting)
2004; 40g + 55g
2006; 80g + 40g
2008; 80g + 40g +160g +30g
2009; 210g + 80g + 40g +160g +30g(bought my first house with big garage/fish room)
2010; 370g + 210g + 80g +40g
2012; 110g (sold house in city and moved back to our home town)
2013; 110g + 500g (set up "dream tank" in new house)
Now; 500g (emptied 110g into 500g)
As you can see it is a growing addiction, fish and tanks come and go as your situation changes, but there is always an ever-increasing trend towards bigger/more! I look at my 2000L tank and it doesn't seem big enough, I like the amount of space my ~18" aro has, and I'd like him to have similar freedom of movement when he is 30"....
I still have the original 10g in the garage, and an empty 40g too. I don't think I'll ever set up the 10g again, it is a fairly ugly home made tank I was given and it is about 1/16th the volume of my current sump, but I still can't part with it!