I have never had a chance to try cyclindrical tanks yet, at lests not for clownfish. I am yet to find an animal that really needs them, maybe the shrimps will.
I agree with david, insulate the environement works wonders, as does having a decent reverse cycle chiller to heat and cool the water, control of water temp gives you greater control of spawning.
personally i use one bigger pump, rather than smaller pumps, first of less power points (im running out) and my biggest pump is the one with the best service life so far, it has done 2 years straight whilst the smaller ones die every 6months to a year. Not to mention having some pressure helps heaps.
I would also add frank hoffs book on rearing of clownfish as a good one.
Good luck
Christian