I started my Whiskey Barrel outside in mid April. Nights were 40s - 60's days 70+. I had a heater in there that is set at 72. On nights under 60 I put a sheet of foam insulation on the barrel.
It has 16 cherry barbs and 3 Zipper loaches in it. Water is 25 gl. I plant to leave it run outside until we get 40degree nights, maybe 1st-2nd wk Oct.?
Your tank might not be as well insulated on the sides as the barrel, but that could be an easy fix with some foam sheeting and duct tape. Not sure how far north you are, I'm 12 mile from the Il/Wisc line. But, I'm sure you could have a pretty long season.
Mine gets Sun until 2pm. The trees block the Sun at different times from dawn until 2. I think it gets full Sun for 3hrs. Last Friday when we broke 100degrees the barrel was 86 on the surface. I have a raised plastic grid in there that my potted Aquarium plant are on to get them closer to the surface. The fish have a shaded place to take cover.
I suggest you consider location and photo period. You don't want to boil the tank. Heat on cold nights is eaier to deal with than excessive heat.
BTW - I have the REDDEST cherry Barbs I've ever seen, and maybe the fastest.
If you address temps. you can keep what you want. Keep in mind Cool water fish like White Clouds are just that COOL water fish. They really don't want to live in 86 degree water. Betas & Paradise Fish are tough and will tolerate a lot but they don't care for high temps either.
Good luck with you project.
Last edited by DogFish; 07-09-2012 at 02:47 AM.