I saw a couple grown ones in the US (Yay, Seaworld! Hehe) and I'd love a tank big enough for them.
Afterwards I saw a couple for sale in a fish shop. Couple little babies like 6 inches long for about $100 if I remember right.
I have 2, one to divide off the chamber the overflow enters and another to divide off the pump section. Only time I get bubbles is when my topoff barrel runs out of water and the pump section starts running low.
I was going to say that waiting 3 weeks would be redundant as the fish have already JUST gone through a 6 week(IIRC) quarantine. But you're in canuckia, don't think they have quarantines?
Anyway, I'd say buy the fish you want quarantine it yourself.
I had one of my tanks heaters unplugged for 2 weeks over winter. Fish were moving slower, but were just fine, including my brazilian puffer. Temp was 16° when I noticed.
You'll be wanting something more like a pond pump than a powerhead. Something along the lines of a Laguna PJ5000 or two should do it. How much flow are you looking for?
Hmmm, Last time I went to Mitre 10 they had 30mm(Or something like that, fairly large anyway) for only $2-3 meter and smaller diameter stuff that's the diameter most gravel vacs use for $2/m VERY cheap.
Put another heater in each. 300W in the bigger tank is definitely not going to do it over winter if it's not insulated. Summer will be fine. My tank is just slightly bigger and over winter going flat out the heater keeps it just above 24.
1: Yes the numbers on heaters are BS. It's well known and has been that way forever.
2: Why do you want your tank so hot?
3: If the heaters won't heat it over 27 when turned all the way up the tank is either stagnant and you have a hot bubble around the heaters and the rest cold or you need bigger heaters.