I did think about doing that and I had spec'd it out. but with the limited room I have, it would have meant loosing two tanks, and Id rather do water changes and have more tanks
Doing changes isnt that bad, I tend to do one or two every day, as I work from home I can nip out and do one or two at lunch then another while tea is cooking, and then on a weekend I might do the big tank and vacuum them etc its a bit of effort, but if I dont change the water for a week they arent gonna die.
I have had very successful tanks in the passed that I only ever topped up the water and the fish spawned and fry were raised in those tanks. its all about balance
Edit: @Josh I was always at the end of the day and got marked off for random stuff, a lot of it was other drivers. luck of the draw, always try to get in early in the month as the later you leave it the closer they are to their targets and they cant pass any over their targets (/me stops derailing again)