Here's a link
http://www.pacergroup.net/Categories17.aspx?Id=Circuit_Breaker_A_Single_Pole
Almost all these breakers are manufactured by carling. Brand doesn't matter.
Mike: You probably all ready did but have you checked your wire size and the length of the run. Going from 10 amps to 30 amps may require going up a size or 2 on the wire.
... Do I need to worry about the size of the wire providing power TO the breaker?...
If each breaker is fed by an individual wire, yes, however I bet your breakers are fed via a "hot buss" (brass strip) with only one wire from your main AC panel to the buss. If you main panel breakers are 30 amps and you have 10 gauge wire to the buss, you should be OK but if in doubt I'd get an ABYC electrical tech to help or offer guidance.
A 30 amp breaker sounds big for the SeaEra system. I installed one and used a 25 amp breaker. I hope I put the right one in.